an expository essay on ebola virus

Expository Essay on Ebola Virus

Jump ahead to:

Here you have an Expository Essay on Ebola Virus, Lets start with the introduction.

Introduction

The Ebola virus is one of the most dangerous and deadly viruses known to humans. The Ebola epidemic since its discovery in 1976 came from the Democratic Republic of Congo, formerly known as Zaire, but the largest Ebola outbreak known to date is still ongoing at the time of writing, in the West Africa. An estimated 550 000 reported incidents from Sierra Leone and Liberia took place on January 20, 2015.

The virus is prevalent in many countries including Guinea, Liberia, Sierra Leone, Nigeria as well as occasional reported cases in the USA, Canada. The Netherlands and India show the potential for infection to spread globally. Despite the fact that the disease is highly contagious, life-threatening, and no specific treatment is available, it can be prevented through the use of appropriate measures to prevent and control infection. The study of the Ebola virus is important as such knowledge will pave the way for the reduction of victims, the development of an effective drug and will be useful in controlling the same epidemic.

The Ebola virus is a member of the Philoviridae family. As the name implies the virus has a filamentous shape. Marburg virus and Ebolavirus are two major generations of the virus family that are important in medicine. Bacteria of these two species are studied and presented together due to their many similarities in the life cycle, water storage areas, transmission methods, clinical presentation, treatment and prevention measures. The only difference is that Marburgvirus is still distributed by forest-dwelling bats such as the savannah while Ebolavirus is distributed by bats species accustomed to deep rain forests.

Five subspecies of Ebolavirus, namely, Ebolavirus Zaire, Ebolavirus Sudan, Ebolavirus reston, Ebolavirus cote d’Ivore, and Ebolavirus bugs, have been identified and named after the place where they were first discovered. Of these E. Zaire was the first to be isolated and studied and is responsible for a large number of outbreaks  including recent outbreaks in 2014 before that E. Sudan accounted for ¼ of all Ebolavirus deaths. With the exception of a slightly lower mortality rate, E. Sudan is almost identical to E. Zaire. E death rate of E case. Sudan is reported as 40-60% and E. Zaire as 60-90%.

Ebola was originally transmitted to humans as a zoonosis. Different species of bats are found throughout sub-Saharan Africa such as. Contact with bats by biting and scratching or exposure to their discharges and discharges through broken skin or mucous membranes can cause infection in humans. The infection can also be spread to other end users. Those recorded in Africa are deer, wildebeests, chimpanzees, chimpanzees, gorillas, monkeys, and other non-humans. Attacks during the hunting of these animals or handling carcasses of infected animals have led to the introduction of the virus to humans from the wild. Outbreaks appear to be exacerbated during pregnancy and in childbirth. Records show that outbreaks appear to be exacerbated by the presence of multiple pathogens.

EVD is highly contagious. Infection can be spread in the community and in a hospital setting by direct contact with infected body fluids such as blood, fluid and discharge or the patient’s tissues or by direct contact with contaminants such as clothing and bed linen. One of the main reasons for the rapid spread of the epidemic is traditional funeral rites, which include cadaver cleaning, removal of fingernails, toenails and clothing. Caregivers, including health workers, are also at greater risk of contracting the disease. In addition the sperm of the surviving male is said to remain infected for up to 82 days after the onset of symptoms. As long as the virus stays in the body fluids a person stays infected. The spread of the Ebola virus is highly suspected but has not been proven by experiments.

Clinical Introduction

EVD caused by different types of Ebola virus brings different clinical features. The incubation period of Ebola virus is generally considered to be 2 – 21 days. Ebola virus disease shows a variety of symptoms that develop deep in the prodromal constitution leading to various diagnoses including not only other viral hemorrhagic diseases, but also malaria, typhoid, cholera, and others. bacterial rickettsia and non-infectious causes of bleeding.

The onset of the disease is similar to that of severe hemorrhagic fever. Patients have high fever, fever reaching 39-400C, body aches and fatigue. Subsequent abdominal symptoms such as epigastric pain, vomiting and / or bloodless diarrhea appear if the fever persists throughout the day. 3-5.

After 4 – 5 days of illness macular degeneration may be visible but may not be clearly visible on dark skin. After this stage the bleeding from different areas begins. Bleeding in both the upper and lower digestive tract, the respiratory tract, the urinary tract, the vagina in women can be detected. Continuous petechial in the buccal mucosa, skin and conjunctivae grow. Repeated cleansing bumps that prevent any oral fluid intake and a large amount of wet diarrhea (five liters or more per day) contribute to the loss of excess fluid leading to dehydration. If fluid changes are not enough, bending, extreme fatigue and hypovolemic shock eventually.

Hypovolemic shock was reported in 60% of cases. Despite high body temperature, patients experience cold edges due to peripheral vasoconstriction. Rapid and cord pulses, tachypnea, oliguria or anuria can be detected. At the same time features such as asthma and abdominal pain, muscle and joint pain and headache increase. Although in some cases coughing and dyspnoea occur as a result of pulmonary haemorrhage, other respiratory symptoms are uncommon. Conjunctival injection is a common clinical feature. The most common neurologic symptoms are hypoactive and hyperactive delirium characterized by decreased mental function, confusion, dizziness and unusual tremors. As the disease changes the internal bleeding may also begin but more often by this time the patients are already in a coma.

It is reported that only 5% of patients have bleeding from the gastrointestinal tract before death. Most of the reported deaths occurred as a result of shock during the 7th to 12th day of illness. Symptoms of 40% of patients have improved by day 10 although symptoms such as mouth sores and thrush have already appeared. Most patients who survived until day 13 showed a high chance of finally recovering. Some patients who showed early improvement in symptoms have had stiff necks and reduced cognitive levels associated with late death.

Post-mortem examinations and post-mortem biopsies are very useful in the study of the pathology of the Ebola virus disease. Because of the biosafety risk in autopsy staff when handling models, pathological explanations of only a limited number of available conditions.

The most common findings of Haematoxylin and eosine-stained tissue components are oval-shaped or filamentous eosinophilic intracellular inclusions formed by a combination of viral nucleobases. These implants can be found in macrophages, hepatocytes, endothelial cells, fibroblasts of connective tissue etc. Immunohistochemically stains express viral antigens to various infected tissue cells including macrophages, dendritic cells, epithelial cells and sweat glands, intermediate cells and kidney tubes. , seminiferous tubes, endothelial cells and endocardial cells. In addition necrotic cells and cellular waste contain antigens in abundance. Electron microscopy shows an abundance of free viral particles in the alveolar glands, liver sinusoids, and connective tissue cells of the testis and dermal collagen. Karyorrhexis and apoptosis are found in portal triads cells, macrophages of the red spleen pulp and epithelial cells of the tubular kidneys.

Liver tissue exhibits histopathological symptoms including concentrated or widespread necrosis of hepatocytes and central steatosis. Although inflammation is usually mild, hyperplasia of kupfer cells and infiltration of mononuclear inflammatory cells is observed. The infected lung shows congestion, bleeding and intra-alveolar edoema but inflammation is not significant. Concentrated infiltration of mononuclear inflammatory cells is known to occur in the lamina propria of the small intestine and colon. Skin biopsies reveal dermal edoema, concentrated bleeding, petechiae, ecchymosis, and macular rashes. Spleen and lymph nodes show widespread lymphoid depletion due to apoptosis and necrosis. Inflammation of the kidneys is undetectable although acute tubular necrosis is more common. Even if the heart endocardium contains viral antigens, the myocardium does not show significant damage. Brain histology shows panencephalitis and perivascular infiltration of lymphocytes.

The World Health Organization (WHO) has recommended a set of measures to prevent and control infection in health workers, including safety measures to be taken in the various stages of EVD patient management.

1. General precautionary measures

Regardless of the disease, it is recommended that health professionals take precautionary measures when treating all patients, as it is difficult to diagnose EVD patients at the onset of the disease. These are,

2. Doing hand hygiene

Use disposable gloves before handling items that may be infected w ear eye protection and a coat before engaging in procedures that body fluids may predict.

3. Hand hygiene

Hand hygiene should be done using soap and water or an alcohol-based hand sanitizer solution, in accordance with WHO guidelines, before wearing gloves and protective equipment (PPE) after exposure to a patient’s body fluids after contact with a dirty area or equipment after extracting PPE. if the hands appear dirty.

4. Personal Protective Equipment (PPE)

PPE should be worn before entering EVD patient care facilities in accordance with the WHO-recommended order and removed before leaving the care facility. Contact with used PPE on any part of the face or fragile skin should be avoided. PPE covers,

• Non-sterile gloves are the right size
• Non-slip and long-sleeved dress
• Face shield
• Locked shoes that prevent piercing and intrusion

5. Patient placement and management

Suspected or certified EVD patients should be kept in isolation and if possible kept in a single room. Otherwise they must be placed in beds with a gap of at least 1m in between. Visitors should have no restrictions other than those necessary for the patient’s well-being as a parent.

Management of used equipment and other items

It is recommended that equipment such as stethoscopes be refined and disinfected before reuse, if different equipment is not available. Parental equipment, surgical blades, syringes and needles should not be reused. They should be discarded in barrels that are resistant to piercing. All solid non-solid waste should be disposed of in non-leaky bags or bins.

Used linen should be collected from non-perishable bags stored during use. They should be washed with water and detergent, rinsed, soaked in 0.05% chlorine for 30 minutes and then dried.

All barrels must remain upright and must be closed when ¾ is full. Before being removed from the wards the outer surfaces of these containers should be disinfected using 0.5% chlorine.

1. Clean the environment

Cleaners should wear heavy rubber gloves, and non-slip, non-slip rubber boots over PPE. Water and cleaning should be used to clean work areas and the floor of the hospital. This should be done at least once a day. Some dirty areas and contaminants should be cleaned and disinfected using 0.5% chlorine.

2. Biological management

Performing autopsies, post-mortem biopsies and other laboratory tests of certified EVD tissue samples or suspected patients should be minimized and should only be performed by qualified personnel. Full PPE should be worn during template handling. All specimens should be submitted with clearly marked, non-leaky, non-breakable containers, with an antiseptic exterior.

Carcasses should never be washed or embalmed. They should be sealed in two bags, disinfected with 0.5% chlorine and buried immediately. Some cultural and religious practices can be changed if necessary, but body care should be kept to a minimum and full PPE should be worn at all times.

3. In the case of exposure to infected body fluids

All current operations should be safe and dry immediately and PPE should be safely removed. Affected skin should be washed with soap and water and any affected pores such as conjunctiva should be washed with plenty of running water. The person should be tested for fever and other symptoms for 21 days.

4. Pathogenesis

The pathogenesis of the Ebola virus shows similarity to that of most other filo viruses that include immunosuppression, increased vascular permeability and coagulopathy. The Ebola virus enters the scrotum even through skin scratches, either through mucous membranes or by accidental injection. The virus enters monocytes, macrophages and dendritic cells and is carried by lymphatics to circulation. It then spreads to the liver and spleen to infect tissue macrophages and fibroblastic reticular cell. The main cellular targets of this virus are macrophages, dendritic cells and kupfer cells. The Ebola virus shows an interaction between a variety of cellular proteins which is why the infection is characterized by broad tissue and organ tropism.

5. Immunopathology

In many cases of the virus, the immune system plays a key role in controlling the spread of the virus. However the tissues and organs of the fatal EVD cases show less inflammation, which raises the damage to the immune response.

It has been found that the proteins of the structure of filo viruses e.g. VP24 (Virion protein) and VP35 inhibit interferon reactions and thus avoid the host’s natural defences. As previously mentioned, apoptosis of natural killer cells and T lymphocytes was revealed in histopathology describing the suppression of dynamic immune responses.

As with most complex phones, the Ebola virus infection also causes significant release of pro-inflammatory and vasoactive substances. Even if pro-inflammatory mediators promote inflammation and inflammation, the spread of the infection system is not effectively controlled. This is due to vasodilation connected by active ingredients.

6. Endothelial dysfunction and coagulopathy

The virus attacks endothelial cells and endocardial cells and causes injury (18). This causes internal bleeding, fluid and electrolyte imbalance and cardiovascular failure. Endothelial damage leads to platelet aggregation and use. The increased level of inflammatory factors and increased production of surface tissue factor protein in infected monocytes and macrophages promotes coagulation decay. As a result of hepatocellular damage the production of coagulation factors, fibrinogen, protein C and S also decreases. Other social and economic problems associated with the Ebola virus epidemic

In view of the current outbreak, in addition to the large number of lives that have been claimed by the disease, it has created many other serious problems not only in Ebola-affected countries, but also in other African countries.

Agriculture contributes significantly to the African economy. As more and more farmers die of the disease and many leave their farms for fear of contracting the disease, there is a severe shortage of workers in these countries and a decline in food production. The emergence of food shortages in the near future is predicted by experts.

Chocolate companies and many other industries are particularly affected by the shortage of workers. Nigeria and Ivory Coast are the largest cork producing countries but most of the workers are from Liberia and Guinea. International companies such as Nestle and Mars have introduced education and fundraising programs to prevent the spread of the virus to cork workers.

Many schools have been closed because of a deadly epidemic that has swept across the country. Apart from the impact on education, the child support system in government has stalled as a result.

Tourism is another area affected by the epidemic. Although Africa is a larger continent than Europe, the USA and China combined; visitors often see it as a single country since the Ebola epidemic broke out. For example, Tanzania, a popular wildlife sanctuary, is an East African country, located more than 6,000 miles from the Ebola-affected area. Tanzanian hotels reportedly lost 50% of bookings in 2015.

Many African countries refused to host international events and conferences because of the risk of the Ebola outbreak. For example, Morocco, the host of the Africa Cup of Nations, scheduled for January 2015, is calling for a postponement. The government says, “There is no way we can be serious about the health and safety of Moroccan citizens.”

Download Expository Essay on Ebola Virus

If you want to Download the PDF of the Expository Essay on Ebola Virus you can simply click on the given link it is free of cost.

• Expository Essay on Leadership in 800-850 words | for 6-12 | Free Pdf
• Expository Essay on Science and Technology in 900-1000 words | Free Pdf

1 thought on “Expository Essay on Ebola Virus | 800-1000 words | Free PDF”

Thank you for taking the time to read our blog! We hope that you found it helpful. If so, please leave a comment or rating below, and share this blog with your friends on social media. Thank you again for reading!

Leave a Comment Cancel Reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

Notify me of follow-up comments by email.

Notify me of new posts by email.

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• J Family Med Prim Care
• v.8(7); 2019 Jul

Ebola virus: A global public health menace: A narrative review

Shamimul hasan.

1 Department of Oral Medicine and Radiology, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India

Syed Ansar Ahmad

2 Department of Oral Surgery, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India

Rahnuma Masood

3 Department of Conservative Dentistry, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India

Shazina Saeed

4 Department of Amity Institute of Public Health, Amity University, Noida, Uttar Pradesh, India

Ebola virus disease (EVD), a fatal viral hemorrhagic illness, is due to infection with the Ebola virus of the Filoviridae family. The disease has evolved as a global public health menace due to a large immigrant population. Initially, the patients present with nonspecific influenza-like symptoms and eventually terminate into shock and multiorgan failure. There exists no specific treatment protocol for EVD and only supportive and symptomatic therapy is the line of treatment. This review article provides a detailed overview of the Ebola virus; it's clinical and oral manifestations, diagnostic aids, differential diagnosis, preventive aspects, and management protocol.

Introduction

Ebola, earlier termed as Ebola hemorrhagic fever (EHF), is a critically lethal ailment which primarily affects the humans and nonhuman primates. Ebola virus disease (EVD) occurs due to a virus infection which belongs to the family Filoviridae and genus Ebolavirus .[ 1 ] EVDs has posed diagnostic challenges and has been a universal public health threat since its discovery. While investigating an alleged yellow fever case, Dr. Peter Piot in the year 1976 first detected the disease in Zaire, Africa (presently the Democratic Republic of Congo).[ 2 ] The name “Ebola” was termed as the disease was noticed near the Ebola river in Congo.[ 3 ]

Fruit bats of Pteropodidae family, such as Hypsignathus monstrous, Epomops franqueti , and Myonycteris torquata serve as the natural hosts of the EBOV in Africa. Nonhuman primates may develop the infection by eating the partly eaten fruits and may also transmit the infection to humans.[ 4 ] Indian population is an impending threat to EVD, as India falls in the home range of Pteropodidae family of fruit bats.[ 5 ]

Ebola virus transmission primarily takes place through close bodily contact with the infected patient or their fluids, contaminated tissue surfaces, and clothing from alive, infected or deceased individuals. Unsafe traditional burial practices also play a pivotal role in the disease transmission.[ 6 ] There is documented evidence regarding the sexual mode of disease transmission, although transmission through the air is unlikely.[ 7 ]

EVD present with bizarre and atypical manifestations mimicking other viral diseases, especially in the initial disease phase. Constitutional symptoms, such as fever, myalgia, headache, vomiting, and diarrhea are the early presenting features. Hemorrhagic rash, internal and external bleeding are usually the warning manifestations in the late stages.[ 8 ] Bleeding from the body apertures is a distinguishing EVD manifestation.[ 9 ] Gum bleeding, odynophagia, and atypical oral manifestations constitute the oral features of EVD.[ 10 ]

Till date, there is no precise antiviral management or vaccination for EVD. The management protocol mainly relies on supportive and symptomatic therapy, along with monitoring coagulopathies and multiorgan dysfunction.[ 2 ]

The World Health Organization (WHO) affirmed the EVD outbreak as a “Public Health Emergency of International Concern” on August 8 th , 2014.[ 5 ]

With the enormous immigrant population, India is estimating the likelihood of a probable EVD outbreak. The Ministry of Health and Family Welfare, Government of India, in collaboration with other agencies has appraised the situation and recommended travel instructions by air, land, and sea and health care professionals.[ 11 ]

The virus belongs to the Ebola virus genus, Filoviridae family, and Mononegavirales order.[ 12 ] The genus Ebolavirus includes the following species- Zaire ebolavirus (EBOV), Reston ebolavirus (RESTV), Bundibugyo ebolavirus (BDBV), Taï Forest ebolavirus (TAFV), Sudan ebolavirus (SUDV), and the newly identified Bombali ebolavirus (BOMV).[ 13 ] Except for exclusive identification of RESTV in the Philippines, all the other species causes endemic West African EVD.[ 14 ]

EBOV responsible for the EHF causes the highest human mortality (57%–90%), followed by SUDV (41%–65%) and Bundibugyo virus (40%). TAFV has caused only two nonlethal human infections to date, whereas RESTV causes asymptomatic human infections.[ 15 ]

Figure 1 shows the taxonomy of Ebola virus.

Taxonomy of Ebola virus

Transmission

Based on the Centers for Disease Control and Prevention (CDC) classification, Ebola virus is considered as a biosafety level 4 and category A bioterrorism pathogen with an immense likelihood for massive nationwide transmission.[ 16 ]

Source of Infection

Intimate physical contact with the patients in the acute disease stages and contact with the blood/fluids from the dead individuals constitutes the most important modes of transmission.[ 17 ]

The long-established funeral ceremonies in the African countries entail direct handling of the dead bodies, thus significantly contributing to the disease dissemination. Unsafe conventional burial procedures accounted for 68% infected cases in 2014 EVD outburst of Guinea.[ 18 ]

EBOV RNA may be identified for up to a month in rectal, conjunctival, and vaginal discharges and semen specimens may demonstrate the virus presence up to 3 months, thus signifying the presence of EBOV in recuperating patients.[ 14 ] The sexually transmitted case of EVD has been reported between a convalescent patient and close family member. Another study demonstrated a case in a recuperating male patient. The patient's semen specimen tested positive with Ebola viral antigen almost 3 months after the disease onset.[ 19 ]

Asymptomatic EBOV carriers are not infectious and do not have a major role play in the EVD outburst, and the field practice in Western Africa supported this assumption.[ 20 ] However, this presumption was refuted after the documentation of a pioneer asymptomatic carrier case in North Gabon epidemic (1996).[ 21 ]

EBOV has been detected from blood, saliva, semen, and breast milk, while RNA has been isolated from sweat, tears, stool, and on the skin, vaginal, and rectal swabs, thus highlighting that exposure to infected blood and bodily secretions constitute the major means of dissemination.[ 22 ]

Eating uncooked infected animal meat such as bats or chimpanzees account significantly to oral EVD transmission, especially in the African countries.[ 23 ] The demonstration of the Ebola virus in the Filipino pigs in 2008 triggered the likelihood of an extensive range of possible animal hosts.[ 24 ]

EVD dissemination has also been reported with hospital-acquired infections, particularly in areas with poor hygiene conditions. The infected needles usage was responsible for the 1976 EVD outbreak in Sudan and Zaire.[ 25 , 26 ] Improper hygiene and sterilization were the crucial factors for the 1967 Yambuku EVD outburst.[ 27 ]

EVD dissemination may also occur through the inanimate materials with infected body secretions (fomites).[ 19 ] However, disease transmission through the airborne and droplet infection is ambiguous.[ 10 ]

Figure 2 shows the primary and secondary transmission of disease.

Primary and secondary transmission

Table 1 depicts the possible routes of transmission.

Possible routes of transmission

Epidemiology

The vast majority of EVD cases and outbursts have been endemic to African continent ever since the disease detection in 1976,[ 28 ] and 36 such outbreaks have occurred in six African countries.[ 29 ]

Table 2 shows Ebola epidemiological outbreaks between 1976 and 2014.

Ebola outbreaks between 1976 and 2014 (Adapted from WHO 2014)

UVRI: Uganda Virus Research Institute; CDC: Centers for Disease Control and Prevention

The 2014–2016 EVD started in South East Guinea rural surroundings and eventually became a global public health menace by rapidly disseminating to urban localities and other countries.[ 28 ]

Figure 3 depicts the geographical distribution of Ebola virus disease.

Geographic distribution of Ebola virus disease outbreaks

The conducive environmental surroundings of the African continent facilitate EVD endemicity. However, intermittent imported Ebola cases have also been noticed in United States, United Kingdom, Canada, Spain, and Thailand.[ 30 , 31 ]

Figure 4 depicts the distribution of Ebola virus disease in West African Countries.

Distribution of Ebola virus disease in West African Countries

Out of the unparalleled globally reported 28,616 cases and 11,310 casualties, Liberia accounted for almost 11,000 cases and over 4,800 deaths.[ 32 ]

Table 3 shows the statistics of the 2014–16 West African outbreak.

Statistics of 2014-16 West African outbreak

Pathogenesis

Ebola viruses penetrate the human body through mucous membranes, skin lacerations/tear, close contact with infected patients/corpse, or by direct parental dissemination.[ 33 ] EBOV has a predilection to infect various cells of immune system (dendritic cells, monocytes, and macrophages), endothelial and epithelial cells, hepatocytes, and fibroblasts where it actively replicates by gene modulation and apoptosis and demonstrate significantly high viremia.[ 34 ] The virus reaches the regional lymph nodes causing lymphadenopathy and hematogenous spread to the liver and spleen promote an active inflammatory response.[ 35 ] Release of chemical mediators of inflammation (cytokines and chemokines) causes a dysregulated immune response by disrupting the vasculature system harmony, eventually causing disseminated intravascular coagulation and multiple organ dysfunction.[ 36 ]

Figure 5 demonstrates the pathogenesis of Ebola virus disease.

Pathogenesis of Ebola virus disease

Clinical Features

Due to the bizarre and atypical manifestations in the initial phase, mimicking dengue fever, typhoid fever, malaria, meningococcemia, and other bacterial infections, EVD poses diagnostic dilemmas.[ 37 ]

The incubation period ranges from 2 to 21 days. However, symptoms usually develop 8–11 days following infection.[ 38 , 39 ]

The initial disease phase is represented by constitutional symptoms.[ 40 ] High-grade fever of >38 o C is the most frequently reported symptom (85–95%), followed by other vague symptoms such as general malaise (85–95%), headaches (52–74%), dysphagia, sore throat (56–58%), and dry cough.[ 41 , 42 ] The progressively advanced disease is accompanied by abdominal pain (62–68%), myalgia (50–79%), nausea, vomiting, and diarrhea (84–86%).[ 41 ]

Variety of hemorrhagic manifestations forms an integral component of the late disease phase.[ 38 ] Gastrointestinal tract bleeding manifests as petechiae, hematuria, melena, conjunctival bleeding, contusion, or intraperitoneal bleeding. Mucous membrane and venipuncture site bleeding, along with excess clot formation may also occur. As the features advances with time, the patients experience dehydration, confusion, stupor, hypotension, and multiorgan dysfunction, resulting in fulminant shock and ultimately death.[ 43 , 44 ]

Maculopapular exanthema constitutes a characteristic manifestation of all Filovirus infection, including EVD.[ 45 ] The rash usually appears during the 5 th to 7 th day of disease and occur in 25–52% of patients in the past EVD outbreaks.[ 46 ]

Table 4 shows the clinical manifestations of Ebola virus disease.

Clinical manifestations of Ebola virus disease

Although EVD has a number of similar features with other viral hemorrhagic fevers (e.g. dengue), there are differences that set them apart.

Table 5 depicts the differentiating features of the Ebola virus and dengue virus infection.

Differentiating features of Ebola and dengue virus infection

Orofacial features

Gum bleeding, atypical mucosal lesions, and odynophagia comprise the distinctive oral manifestations. Epistaxis (nasal bleed), bleeding from venipuncture sites, conjunctivitis, and cutaneous exanthema are the other manifestations.[ 9 ] Bleeding tendencies and gum bleeding is not seen in asymptomatic or initial EBOV patients reporting to the dental hospital.

EVD dissemination in the field of oral and dental health may appear nonsignificant; although, probable situations which may pose a risk to dental health professional have been appraised by Samaranayake et al. [ 21 ] and Galvin et al. [ 10 ]

Table 6 depicts the various orofacial manifestations of Ebola virus disease

Orofacial manifestations of Ebola virus disease

EVD patients usually demonstrate altered laboratory parameters based on the stage of the disease.

Table 7 shows the laboratory findings in Ebola virus disease.

Laboratory findings in Ebola virus disease

The WHO (2014) recommended the sample collection of whole blood or oral swab at suitable centres called Ebola treatment centers.[ 47 ] Reverse transcriptase polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) are the most frequently utilized tests for laboratory affirmation of the EVD.[ 43 ] RT-PCR is capable of detecting viral RNA in the blood samples of infected patients immediately after the commencement of signs and symptoms,[ 42 , 48 ] has a high sensitivity (up to 100%), and gives results within 1–2 days in cases of epidemics. ELISA detects the immunoglobulins G and M in samples of infected patients, has a low sensitivity (91%) and is not suitable for initial affirmation during an outbreak.[ 42 , 49 ]

The most imperative strategy in EVD is to avert the vulnerable population from getting infected and limit the transmission. These preventive strategies entail intensive and rigorous endeavors from the Government, public health amenities, medical units, and personals.[ 50 ]

The most essential aspect to curb EVD transmission is to avert direct bodily contact with infected individuals and their body fluids.[ 51 ]

Health caregivers are extremely vulnerable and experience an augmented professional threat for EVD.[ 52 ] Thus, scrupulous adherence to the universal infection control measures is fundamental in all the hospitals, laboratories, and other health care services.[ 53 ] The U.S. CDC has advocated the appropriate use of various personal protective equipment as a mandate for health care professionals.[ 50 ]

The risk of rapid importation of Ebola virus into human beings can be prevented by averting the direct bush meat and bats contact.[ 54 ]

Unsafe traditional burial procedures, especially in the African continent significantly contributed to the EVD transmission. Hence, it is essential to practice safe and guarded funeral rituals to prevent the disease spread.[ 55 ]

WHO recommends the implementation of safe sex practices to combat the sexual transmission of EVD. Strict abstinence or proper and regular condom use in male EVD survivors at least for a period of 12 months of the symptom onset or until their semen has twice tested negative should be followed.[ 56 ]

Dental health care personals are extremely susceptible to EVD as they are in regular contact with blood and saliva during the routine diagnostic procedures. There is no documented case of EVD through saliva till date. A study on the identification of EBOV in oral fluids affirmed that patients presenting with demonstrable serum levels of EBOV RNA also exhibit identifiable salivary levels.[ 57 ] The incubation period for all body fluids including saliva is 21 days; hence, oral health personals are vulnerable to develop the disease if universal infection control protocol is not followed.[ 58 ]

Table 8 demonstrates the various infection control measures to prevent the Ebola virus spread.

Infection control measures to prevent Ebola virus spread

Box 1 shows the travel guidelines to EBOV affected regions.

Shows the UK Travel guidelines to EBV infested regions.

Till date, there is no precise antiviral management or vaccination for EVD.[ 51 ] The management protocol mainly relies on supportive and symptomatic therapy. Public health strategies emphasizing on epidemiological surveillance, contact tracing, and quarantine of the patient have been recommended to combat the dissemination of EVD.[ 59 ]

Rehydration, adequate nourishment, analgesics, and blood transfusion form a keystone supportive treatment of EVD patient.[ 60 ] Intravenous fluids and oral rehydration solution endow with proper electrolytes substitute and maintain the intravascular volume. Unrelenting vomiting and diarrhea are taken care of by the use of antiemetics and antidiarrheal drugs.[ 35 , 60 , 61 ] Suspected cases of secondary bacterial infections and septicemia are best managed by the use of prophylactic antibiotic regimen (third generation I.V. cephalosporins).[ 62 ] Concurrent parasitic coinfections may also be seen and require prompt investigations and management.[ 63 ]

A number of investigative clinical trials emphasizing on the development of vaccine, antibody therapies, and antiviral drugs have been conducted for EVD.[ 64 ]

Table 9 shows experimental treatment for Ebola virus disease.

Experimental treatment for Ebola virus disease

Various clinical trials in Africa, Europe, and the United States suggest that Ebola vaccines are in various development stages (Phase I–III). A number of candidate vaccines employ diverse platforms, including recombinant viral vectors (most evolved vaccine candidate), DNA vaccines, inactivated viral particles, subunit proteins, recombinant proteins, and virus-like particles. Example of viral vectors expressing ebolavirus glycoproteins include recombinant simian adenovirus (cAd3), recombinant vaccinia virus, recombinant human adenovirus (Ad26), and a live vesicular stomatitis virus used alone or in prime-booster regimens.[ 65 ]

However, Ebola virus having the glycosylated surface proteins and preferentially infecting the immune cells impedes the development of an effective vaccine.[ 66 ]

Dental Management

Dental health care professionals in Europe have not encountered a case of EVD so far. However, health care personals (including dental surgeons) are more prone to EVD while treating patients in West or sub-Saharan Africa. Dental professionals are more likely to encounter asymptomatic EVD patients or those with early-stage vague symptoms.[ 27 ]

Individuals with a travel history to Ebola endemic regions, but with no direct intimate contact with the disease fall in the low-risk category and may undergo any medical/dental health care procedures without restrictions. However, all the nonessential procedures should be postponed for 21 days in individuals with direct exposure to the virus. The regional Health Service Executive Department of Public Health needs to be notified when the exposed patient's treatment cannot be deferred or controlled with pharmacotherapy.[ 10 ]

EVD has emerged as a significant global public health menace due to multiple disease outbreaks in the last 25 years. Recent advancements are being carried out in the form of effective Ebola virus vaccine and anti-Ebola virus drugs. However, rapid geographic dissemination, nonspecific clinical presentation, lack of vaccine, and specific diagnostic test are the possible challenges to combat this dreaded public health menace.

Financial support and sponsorship

Conflicts of interest.

There are no conflicts of interest.

• Human Editing
• Free AI Essay Writer
• AI Outline Generator
• AI Paragraph Generator
• Paragraph Expander
• Essay Expander
• Literature Review Generator
• Research Paper Generator
• Thesis Generator
• Paraphrasing tool
• AI Rewording Tool
• AI Sentence Rewriter
• AI Rephraser
• AI Paragraph Rewriter
• Summarizing Tool
• AI Content Shortener
• Plagiarism Checker
• AI Detector
• AI Essay Checker
• Citation Generator
• Reference Finder
• Book Citation Generator
• Legal Citation Generator
• Journal Citation Generator
• Reference Citation Generator
• Scientific Citation Generator
• Source Citation Generator
• Website Citation Generator
• URL Citation Generator
• Proofreading Service
• Editing Service
• AI Writing Guides
• AI Detection Guides
• Citation Guides
• Grammar Guides
• Paraphrasing Guides
• Plagiarism Guides
• Summary Writing Guides
• STEM Guides
• Humanities Guides
• Language Learning Guides
• Coding Guides
• Top Lists and Recommendations
• AI Detectors
• AI Writing Services
• Coding Homework Help
• Citation Generators
• Editing Websites
• Essay Writing Websites
• Language Learning Websites
• Math Solvers
• Paraphrasers
• Plagiarism Checkers
• Reference Finders
• Spell Checkers
• Summarizers
• Tutoring Websites

Most Popular

11 days ago

Why Congress Cares About Media Literacy and You Should Too

How educators can reinvent teaching and learning with ai, plagiarism vs copyright.

12 days ago

Who vs Whom

Top 20 best books on american history, symptoms of the ebola virus essay sample, example.

Ebola was first discovered 1976 in Africa, on the banks of the Ebola river, after which the virus has been named. Back then, there were two major outbreaks of the virus, and this is how people learned about it. There exist several strains of the Ebola virus, some of them are deadly to people, and some are not.

The main symptoms of Ebola can appear in a period between the second and the 21st days of contamination, but usually it happens on the eighth through 10th day (CDC). Among the symptoms that appear in the first turn, one should mention fever and chills, strong headaches, pain in joints and muscles, and general weakness. These symptoms are not too different from those that people usually experience when catching a severe cold, or flu, so victims may even ignore these symptoms, or try to treat them as a common sickness. However, as the virus keeps progressing, a patient develops nausea with vomiting, diarrhea, chest and stomach pains, red eyes and rashes over the body, severe weight loss, and bleeding from almost all bodily orifices (Mayo Clinic).

The virus is usually transmitted either through blood or through waste. Contagion through blood usually takes place if a person consumes infested meat, or even touches it (for example, butchering can also lead to contamination). Also, there were cases when people got infected after stepping in feces of infected mammals, mostly bats (Mayo Clinic). The other ways of getting infected is through skin by receiving bodily fluids through pores.

Even though there is no specific cure from Ebola, doctors still try to treat it. In order to diagnose Ebola, doctors usually take tests on such diseases as cholera or malaria, because it is difficult to diagnose Ebola based solely on symptoms. After the diagnosis has been made, doctors start treating the symptoms, which includes eliminating infected cells, electrolytes, blood pressure medication, blood transfusions, oxygen therapy, and so on (WebMD).

Though Ebola is a highly dangerous disease, it is not likely that it will spread globally. It is most deadly in anti-sanitary conditions, which many African countries are notorious for. As for first world countries, even though there is still no universal cure, they are at much lesser risk than African countries. Though the symptoms of Ebola are severe and getting infected is not difficult, with the correct handling of an outbreak, the virus should not be able to spread.

“Signs and Symptoms.” Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 03 Oct. 2014. Web. 05 Oct. 2014. .

“Ebola Virus and Marburg Virus.” Causes. N.p., n.d. Web. 06 Oct. 2014. .

“Ebola Virus: Symptoms, Treatment, and Prevention.” WebMD. WebMD, n.d. Web. 05 Oct. 2014. .

Follow us on Reddit for more insights and updates.

Comments (0)

Welcome to A*Help comments!

We’re all about debate and discussion at A*Help.

We value the diverse opinions of users, so you may find points of view that you don’t agree with. And that’s cool. However, there are certain things we’re not OK with: attempts to manipulate our data in any way, for example, or the posting of discriminative, offensive, hateful, or disparaging material.

Comments are closed.

More from Expository Essay Examples and Samples

Nov 23 2023

Why Is Of Mice And Men Banned

Nov 07 2023

Pride and Prejudice Themes

May 10 2023

Remote Collaboration and Evidence Based Care Essay Sample, Example

Related writing guides, writing an expository essay.

Remember Me

What is your profession ? Student Teacher Writer Other

Forgotten Password?

Username or Email

Open Access is an initiative that aims to make scientific research freely available to all. To date our community has made over 100 million downloads. It’s based on principles of collaboration, unobstructed discovery, and, most importantly, scientific progression. As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world. How? By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers.

We are a community of more than 103,000 authors and editors from 3,291 institutions spanning 160 countries, including Nobel Prize winners and some of the world’s most-cited researchers. Publishing on IntechOpen allows authors to earn citations and find new collaborators, meaning more people see your work not only from your own field of study, but from other related fields too.

Brief introduction to this section that descibes Open Access especially from an IntechOpen perspective

Want to get in touch? Contact our London head office or media team here

Our team is growing all the time, so we’re always on the lookout for smart people who want to help us reshape the world of scientific publishing.

Home > Books > Emerging Challenges in Filovirus Infections

Essay on the Elusive Natural History of Ebola Viruses

Submitted: 15 April 2019 Reviewed: 29 July 2019 Published: 01 October 2019

DOI: 10.5772/intechopen.88879

Cite this chapter

There are two ways to cite this chapter:

From the Edited Volume

Emerging Challenges in Filovirus Infections

Edited by Samuel Ikwaras Okware

To purchase hard copies of this book, please contact the representative in India: CBS Publishers & Distributors Pvt. Ltd. www.cbspd.com | [email protected]

Chapter metrics overview

1,258 Chapter Downloads

Impact of this chapter

Total Chapter Downloads on intechopen.com

Total Chapter Views on intechopen.com

This chapter presents a review of what is known about the natural history of the Ebolaviruses in Central and West Africa as well as in the Philippines. All the previous hypotheses on the natural cycle of Ebolavirus are revisited. Also, the main factors driving the virus natural cycle are summarized for the different ecosystems where the Ebolavirus is known to have emerged, including the virus species, the date of emergence, the seasonality, the environmental features, as well as the potential risk and associated factors of emergence. The proposed hypothesis of the Ebolavirus natural cycle prevails an inter-species spillover involving several vertebrate hosts, as well as biotic and abiotic changing environmental factors among other original features of a complex natural cycle. It is also compared with other virus having such type of cycle involving chiropteran as potential reservoir and vector and presenting such original inter-outbreak epidemiological silences. Ultimately, these observations and hypotheses on Ebolavirus natural cycles give some insight into the potential drivers of virus emergence, host co-evolution, and a spatiotemporal dimension of risk leading to identify high risk areas for preventing emerging events and be prepared for an early response.

• natural cycle

Author Information

Jean-paul gonzalez *.

• Division of Biomedical Graduate Research Organization, Department of Microbiology and Immunology, School of Medicine, Georgetown University, USA
• Centaurus Biotech LLC, USA

Marc Souris

• Institute of Research for Development (IRD), France

Massamba Sylla

• Ministry of Health, Senegal

Francisco Veas

• Faculty of Pharmacy, Montpellier University, France

Tom Vincent

• CRDF Global, USA

*Address all correspondence to: [email protected]

1. Introduction

It has been several decades since an unknown fever dramatically emerged, close to the Ebola river, a small tributary of the great Ubangi river in the heart of the Congolese tropical forest of Africa. Since that time, even though the virus responsible for this new hemorrhagic fever has been identified and characterized, the natural history of the eponymic Ebolavirus remains largely unknown. The cradle of the virus remains enigmatic and the emergence of the Ebola fever unsolved. Indeed, the arcane of Ebolavirus natural history is still hypothesized, thanks to an elusive virus that always risen where it was not expected, violent and devastating, and surprising local populations and health systems, as well as the international scientific community. This Ebolavirus eco-epidemiology remains complex while the Ebola fever (alias Ebolavirus Disease) can be considered as an exemplary disease that can be eventually comprehended only with a transdisciplinary approach that has recently been promoted as a One Health concept. Indeed, it is only when we take into account all disease and virus drivers, including biotic and abiotic factors of the natural and human environments, that some mechanisms of the Ebolavirus disease emergence, such as spread and circulation, can be ultimately unveiled. For that, we have collected all information available, often estimated, from the time and place of the virus emergence long before the emerging event was identified as it and the epidemic phase was brought to public attention. Moreover, when available we also collect all data on potential natural and accidental hosts, weather and environment chorology, among other multiple factors potentially involved.

Historically, Ebolavirus emerged in Central Africa in the late 1970s, and has re-emerged most recently with the active epidemic (April 2019) in the eastern Democratic Republic of Congo (DRC), by encompassing more than 24 epidemic events from Central to West Africa, to imported infected monkey from Asia to Virginia, and the emerging new Ebola species of the Philippines archipelago [ 1 ].

Among the negative sense RNA viruses of the Filoviridae family five genera are known, including Cuevavirus, Ebolavirus, Marburgvirus , Thamnovirus . Among the Ebolavirus genus, five Ebolavirus (EBOV) species have been identified [ 2 ].

Ebolavirus’ (EBOV) first emergence occurred in 1976, as two different EBOV species in two different places in sub Saharan Africa. The Zaire Ebolavirus (ZEBOV) species and the Sudan Ebolavirus (SUDV) were detected concomitantly, a few weeks apart, respectively in the Northeastern Equator province of the Democratic Republic of Congo, DRC (alias Zaire), and in the Bahr el Ghazal province of South Sudan. On the 26th of August 1976 ZEBOV was isolated from missionaries and local villagers of the Yambuku, in the rain forest close to the Ebola river. However, earlier in June 1976, the SUDV had broken out among cotton factory workers in Nzara, Sudan (now in South Sudan) [ 3 ].

Then, in 1989, the Reston Ebolavirus species surprisingly (RESTV) emerged in the US (!) and was identified during an outbreak of simian hemorrhagic fever virus in crab-eating macaques from Hazleton Laboratories (now Covance) of Reston county, Virginia. Such primate specimens were found to be recently imported from the Philippines. Then, in 1994 a fourth new species of Ebolavirus was isolated from chimpanzee leaving in the Tai Forest of Côte d’Ivoire and named Côte d’Ivoire ebolavirus (CIEBOV). Finally, in November 2007, a fifth Ebolavirus species, was detected from infected patients in Uganda in the Bundibugyo District and was subsequently identified by the eponymic name of Bundibugyo Ebolavirus [ 4 ].

Briefly and extraordinarily among the world of the viruses, the filovirus virion presents a bacilliform (filamentous) shape, like a Rhabdovirus, but presents unique pleomorphic figures with branches and other tortuous shapes. Ebolaviruses have also an unusual and variable long length - up to 805 nanometers (only some plant virus can compete to this filamentous extensive length). However, the internal structure is more classical with a ribonucleoprotein nucleocapsid, a lipid envelope and seven nanometers size spikes. The genome is non-segmented, single stranded RNA of negative polarity with lengths of about 18.9 kb that code for seven proteins, each one having a specific function [ 5 ].

Ebolaviruses are known for their high case-fatality rate (CFR) with always less than 2/3 of survivors among the identified cases. ZEBOV, the most frequently isolated Ebolavirus species during the outbreaks, has the highest CFR, up to 90% in some instances, with an average of 83% for the past 37 years. The Uganda BDBV outbreak had a mortality rate of 34%. RESTV imported to the US did not cause disease in exposed human laboratory workers. The scientist performing the necropsies on CIEBOV infected chimpanzees got infected and developed a Dengue-like fever, fully recovered 6 weeks after the infection while treated in Switzerland.

2. When Ebolavirus raised his head in the heart of darkness

Dates and time make History. Indeed, the various reports on the emergence of Ebolavirus in Africa show discrepancies and lack accuracy, for multiple reasons (remote event, reports by different person or team, at different time…) but the only way to forge the history is to label the events with date, time and the environmental factors observed. On July 27, 1976, the first (known) victim to contract Ebolavirus was a cotton factory worker from Nzara, Sudan. Then, in Zaire (DRC) on September 1, 1976, the first Ebolavirus (Zaire ebolavirus, ZEBOV) victim was a teacher who had just returned from a family visit to northern Zaire (6 Jennifer Rosenberg Internet). These two events were the very beginning of the boundless journey of a deadly Ebolavirus outbreaks.

2.1 The Ebolavirus species emerging events

When the virus becomes epidemic in a human population, it does so weeks or months after the emergent event of the virus switching from its silent transmission in a natural cycle to a zoonotic/epidemic manifestation, revealed to the local health system. Let us see in more detail such emerging events of Ebolavirus species (ICTV, 2018) as there were reported or sometime interpreted, in time and place.

Sudan ebolavirus (SEBOV) occurred when the first recorded SUDV broke out among cotton factory workers in Nzara, South Sudan in June 271,976. This was indeed, the first case of Ebolavirus infection recorded and confirmed and also reported as potentially exposed to chiropteran. Indeed, at the Nzara Cotton Manufacturing Factory this first patient was a cloth room worker where bats (mostly Tadarida - mops - trevori ) have a large population in the roof space of their premises. He died in the Nzara hospital on July 6, 1976. Local animals and insects were tested for Ebolavirus without success [ 6 , 7 ].

Zaire ebolavirus (ZEBOV) was reported in the Mongala district of the Democratic Republic of Congo (DRC; alias Zaire) in August 1976, when a 44-year-old schoolteacher of the Yambuku village, became the first recorded case of Ebolavirus infection in DRC. Also, the schoolteacher travel earlier in August 1976 near the Central African Republic border and along the Ebola River, estimated 90 km NW from the village [ 6 ].

Reston ebolavirus (REBOV) had its first emerging event as an imported infected cynomolgus monkey ( Macaca fascicularis ) in October 1989 imported from a facility in the Philippines (Mindanao Island) to Reston, Virginia, USA, where the primate got sick and the virus isolated [ 8 ]. In the Philippines, in several instances, the virus was found to infect pigs, in June and September 2008 ill pigs were confirmed to be infested by REBOV (Ecija and Bulacan, Manila island), as well during 2008–2009 epizootics in the island of Luzon (Philippines) [ 9 ].

Cote d’Ivoire ebolavirus (CIEBOV) was isolated for the first time, and as an only known appearance, in November 1994, from wild chimpanzees presenting severe internal bleeding of the Taï Forest in Côte d’Ivoire, Africa. A researcher became infected when practicing a necropsy on one of these primates, he developed a dengue syndrome and survived. At that time, many dead chimpanzees were discovered and tested positive for Ebolavirus. However, the source of the virus was believed to be of infected western red colobus monkeys ( Piliocolobus badius ) upon which the chimpanzees preyed [ 10 ].

Bundibugyo ebolavirus (BDBV) was then discovered during an outbreak of Ebolavirus in the Bundibugyo District (Bundibugyo and Kikyo townships), on August 1st, 2007, in Western Uganda (Towner et al. [ 11 ]). BDBV second emerging event was observed in the DRC in August 17, 2012 in Isiro, Pawa and Dungu, districts of the Province Orientale [ 11 ].

With the exception of REBOV in Philippines and CIEBOV in West Africa, all other EBOVs species emerged in the Central African region. Also, all EBOVs are known to emerged in the tropical rain forest during the inter-season between dry and rainy seasons. Also, REBOV appears to actively circulate in the tropical rain or moist deciduous forest of the Philippines [ 12 ].

2.2 From Central Africa to West Africa

2.2.1 concurrent emergences of ebolaviruses.

On several occasions, concurrent emerging events of Ebolavirus have been observed. Indeed, such events occurred in places geographically distant, independent, and unconnected. The Ebolavirus was isolated and the strains different, even they belonged to the same species of Ebolavirus, altogether in favor of a different origin from an elusive natural reservoir, thus eliminating the notion of leaping from one site to the other. In that matter, the following observations are a paradigm: From its inceptive emergence the Ebolavirus was identified in Sudan at the cotton factory and a few days later at Yambuku, Zaire. The Ebola Sudan and Ebola Zaire viruses emerged concurrently in 1976 in the Congo basin of Central Africa; More than 20 years later the virus emerged and reemergence from 1994 to 1996 in a different places in Gabon, in a successive and timely overlapping events but in unconnected areas from where different strains of the same EBOVZ were isolated [ 13 ]; More recently, during the 2014–2016 dramatic Ebolavirus disease (EVD) emergence of in West Africa where the virus emerged in late December 2013 of a 18-month-old boy from the small village of Meliandou (Guéckédou district, South-Eastern Guinea) believed to have been infected by bats [ 14 ], concurrently, in August 2013, the Ebolavirus reemerged in the Equator province of DRC - different places and different strain of ZEBOV [ 15 ].

It is remarkable that most of these emerging events occurred during or close to the end of the rainy season which generally stretches from August to October in the domain of the Congo basin tropical rain forest.

Altogether, these observations are in favor of environmental factors of emergence favoring, when they occur synchronously in the same place, the spillover of the virus from its hidden natural cycle to an accidental and susceptible host. Therefore, these plural and concomitant emerging events play against the theory of Ebola virus diffusing in oil spot in Central Africa [ 16 ]. This original pattern of concurrent emergences could explain also the relative stability of the virus strains which remain for years in the same environment, and the interepidemic silences which require several fundamentals (i.e. concurrent risk factors) to be broken.

2.2.2 An unexpected broader domain of Ebolavirus circulation

The first evidence that showed that Ebola virus had previously circulated in areas without any known cases of disease came in 1977, near the Ebola outbreak in Tandala, DRC, just 200 miles west of the first known cases in 1976 [ 17 ]. Blood samples obtained from individuals in areas with no previous symptoms of Ebola were found to contain antibodies for Ebolavirus, indicating a previous or ongoing infection with that virus. Because subclinical illness is always a possibility with viral infections, the presence of these Ebolavirus-specific antibodies could only be explained by exposure to the virus, which is somewhat reasonable in an area that is endemic to the disease. But how do we know the true endemic zone of a virus such as Ebolavirus?

Endemic zones are primarily based on where disease can most likely be expected, and are determined by historical accounts of disease, as well as supplemental information such as where animals or insects that might transmit the disease are located. With respect to the Ebola virus, outbreaks that occur in Central Africa, in or near the Congo River Basin, are expected; outbreaks that take place elsewhere are unexpected and can be problematic, as was the case for the 2014–2016 West African outbreak. And yet, scientists have highlighted the presence of Ebola antibodies well outside the endemic zone for disease for decades.

In the early 1980’s, research based at the Pasteur Institute in Bangui, Central African Republic, demonstrated for the first time that the population of central Africa presented natural antibodies against the Ebolavirus strains of Zaire and Sudan [ 3 , 4 ]. Research also showed for the first time that several mammal species had Ebolavirus-reacting antibodies, including rodents, dogs, and others. Initially, the scientific community was skeptical of the findings, due to the type of antibody tests used, and because the prevalence of these antibodies was unbelievably dispersed and at a high level of prevalence. However, a 1989 follow-up study confirmed methodology and preliminary observations, and expanded the results to include similar observations in Cameroon, Chad, Gabon, and Republic of Congo (the latter two of these countries would have their first Ebola outbreaks in 1994 and 2001, respectively) [ 5 ]. Moreover, such Ebolavirus antibody prevalence was found in West Africa (e.g. Senegal, Chad, Sierra Leone), preceding the catastrophic 2014–2016 Ebolavirus outbreak [ 18 ]. Subsequent studies have determined that 20–25% of persons living in or near the Congolese rain forest are seropositive for Ebola, despite never exhibiting symptoms [ 19 ].

Today, Ebola antibody prevalence is widely distributed across the African continent in the absence of severe clinical presentation and/or outbreak manifestation. A 1989 study even found Ebola Zaire antibodies among people living in Madagascar, an island country that has never had a single known case of Ebola, and which has been geographically separated from continental Africa for 100 million years [ 20 ].

Risk mapping, including ecological and geographical distribution <10-13 cm/s first hour, and extended, highly sensitive and specific environmental and biogeographical models based on EBOVs susceptible mammalian biogeography in Africa, show a robust and precise potential distribution of EBOVs in Africa that clearly overlap the African tropical rain forest biome of the Guinea-Congo forests (including the Congo basin rain forest, and the Occidental relic of the Congolese rain forest spreading from Guinea to Ghana) and the southern band of the Sudan-Guinea Savanna [ 21 ].

Also, as a result of potential Ebolavirus (or Ebolavirus antigen) exposure, serological markers have been found in vertebrates outside of Africa. With the exception of Philippines, where REBOV is known to circulate in monkeys and pigs, thus showing its ability to infect multiple animal species, in several instances serological evidence of Ebolavirus exposure has been detected in many vertebrates, particularly chiropterans [ 9 ]. Definitely, bat populations in Bangladesh and China present antibodies against ZEBOV and REBOV proteins [ 22 , 23 ]. Ultimately, it appears that EBOVs are widely distributed throughout Africa, West and Central, and Asia. Moreover, risk mapping of filovirus ecologic niches suggests potential areas of EBOVs distribution in Southeast Asia [ 24 ].

The unexpected detection of REBOV first in Virginia, for the reason we know, and then the astonishing discovery of its circulation and natural cycle in the Philippines gave a rethinking of the entire family of Ebola viruses previously known mainly on the African continent [ 25 ].

From these observation and facts, the potential circulation of EBOVs in its natural cycle appears much wider than expected, while the emerging events we can witness appears to be only a tip of the iceberg in the wide Congolese tropical rain forest.

2.3 From the index case to the epidemic chain, outbreak, and pandemic

The fundamentals of emergence are changing in the heart of the rainforest and elsewhere: changing times, when the means of transmission switch from foot to motorbike, when knowledge conveyance has switched from paper reporting to the internet.

Let us examine the risk of expansion for Ebolavirus. Indeed, the factors of transmission of the virus to man and man to man are essential to take into account in this context. Moreover, it is extremely important to note that these factors are subject to permanent changes in societies whose trade and means of communication are drastically changing as a result of health systems, responses and preparedness for epidemics at national and international levels, policies, and the economy.

So, with the experience gained for more than 40 years, the strategies of struggle are clearly defined, but the societal changes that are taking place make their application difficult and sometimes impossible (e.g., the 2019 outbreak in the DRC, where political institutions have prevented an adapted response). Situation and the epidemic are perpetuated.

There is also a growing means of communication, both smartphones and motorized transport, to travel more quickly as ever, between the epidemic zone of EVD and the family [ 26 ].

Thus, during the emergence of the Ebola virus in West Africa, all of this means of communication played a fundamental role in the regional spread of the epidemic, until it became a pandemic risk when the virus was exported to other countries of the African continent and, outside Africa in Europe and North America [ 27 ].

3. A strange iteration of epidemic events with unexplained virus disappearance

It is known for several other transmitted viruses that during the inter-epidemic silences several factors can be responsible. In general mass herd immunity (natural of due to acquired immunization i.e. vaccine) of the permissive hosts force the virus in its natural cycle without apparent clinical manifestation in the hosts (e.g. Most by the arbovirus classically yellow fever, Dengue, Japanese encephalitis, West Nile, Zika etc.).

The Paramyxoviridae and Rhabdoviridae are the two other viral families in the order Mononegavirales, genetically closely related to the Filoviridae and having chiropteran as reservoir and/or vector [ 28 ]. Indeed, it is interesting to note that megachiropteran fruit bats are reservoirs of Hendra and Nipah viruses of the Paramyxoviridae family [ 29 ]. When, Microchiroptera bats are the probable ancestors of all rabies virus variants of the Lyssavirus genus in the family Rhabdoviridae and infecting presently terrestrial mammals [ 30 ]. Both also present this cryptic interepidemic silences that has not been yet clearly understood. The Nipah emerged one time in Malaysia (1999), thought to have its original cycle in PNG, and ultimately reemerged more than 3500 km away in Bangladesh in 2001. From its inception, again the Marburgvirus (the closest to EBOVs in the family of Filovirus), emerging events from an expected natural foci occurred within the path of time including 4 to 11 years of inter-epidemic silences occurring mostly in distant sites of Eastern and South Africa (Uganda, Zimbabwe, Angola, Kenya).

If one were to describe the history of Ebola outbreaks, one could simply construct a timeline, with a point on the line for each outbreak. You could create this timeline with a varying number of points, depending on your methodology, but regardless of how you built your timeline, there would be spaces between these points. This is due to the nature of Ebola; it appears, it disappears, and it appears again. To the Ebola virus, these gaps are periods of convalescence. To us, they are periods of absence and mystery, and one of these gaps stands out as the most mysterious ( Figure 1 ).

Timeline of Ebolavirus emergence. Emerging events (bars) red = EBOV; blue = SEBOV; green = BDBV; horizontal axis = years 1972–2018; vertical axis = no value. Numbers above brackets = years of silent inter-emerging event.

The CDC lists five Ebola outbreaks in the late 1970’s. The “first” Ebola outbreak took place in 1976, though we now recognize the event as two simultaneous and separate outbreaks. Between June and November 1976, 284 cases (151 deaths) of Ebola Sudan occurred near what is now Nzara, South Sudan; between September and October 1976, 318 cases (280 deaths) of Ebola Zaire occurred near what is now Yambuku, Democratic Republic of Congo (DRC). In November 1976, a researcher in England that was working with samples from the Nzara outbreak accidentally infected himself; CDC lists this accident as the third Ebola outbreak (the individual recovered). In June 1977, a child became sick and died from Ebola Zaire in Tandala, DRC though there was only one confirmed case, subsequent epidemiological investigations of the area uncovered several other historical, probable cases. Finally, between July and October 1979, 34 cases (22 deaths) of Ebola Sudan occurred, unbelievably, in Nzara, Sudan – the same community where the first cases of Ebola emerged just 3 years prior. In the span of just 39 months, the terror of Ebola had introduced itself to the world five times (638 cases, 454 deaths) and then… silence.

Ebola would not reappear for 10 whole years, and even then, the subtype was Ebola Reston, which we now know does not affect humans. Though CDC lists four Ebola Reston outbreaks between 1989 and 1992, the world would not see another case of Ebola virus disease in humans until late-1994, in Gabon. Even then, the outbreak (52 cases, 31 deaths) was mischaracterized as yellow fever for several months. Perhaps the virus’s long absence from the spotlight had removed it from the collective consciousness in 1994, certainly in the presence of those pathogens that had been circulating and consuming our attention in the meantime.

This fifteen-year disappearance of Ebola, particularly in light of its frequent and severe outbreaks in the late 1970’s, has perplexed researchers for decades. The mystery lay, to some extent, within the lack of complete knowledge of the virus reservoir, though scientists are now having their long-held suspicions in bats confirmed. It’s hard to detect disease when you cannot pinpoint the source. Surveillance and reporting have been another confounding element. How many times in that fifteen-year period was an illness misdiagnosed as yellow fever, dengue hemorrhagic fever, or some other similar illness, because of lack of knowledge or diagnostic capabilities, or simply because there was no health care around? We will probably never be able to answer this question. Finally, our perceived zone of endemicity at the time was limited to northern DRC and southern Sudan. Was the virus appearing elsewhere, unbeknownst to us? We certainly were not expecting it to emerge in Gabon in 1994, and Uganda in 2000, and West Africa in 2014 [ 31 ].

Scientists today continue to be perplexed by the emergence of the virus. What brings Ebola out from its hiding place? Is its emergence/re-emergence tied to climate change? globalization? the changing interface between humans and wildlife? If it has to do with any of these increasingly significant factors, how do they explain the fifteen-year disappearance?

These days, the virus comes and goes with some predictability—since 2000, outbreaks have approached a near-annual incidence, sometimes skipping a year, sometimes lasting more than a year. The periods between outbreaks are growing shorter. Is this because our capability to detect Ebola outbreaks is improving, or is the virus able to infect humans more frequently? One thing is for sure: the world knows that when one outbreak ends, another will eventually follow, and we need not wait 15 years.

4. Toward the discovery of the natural cycle of the Ebolaviruses

4.1 the discovery of a putative natural reservoir of ebolavirus.

Since the ZEBOV and SEBOV emergence, extended field studies have been conducted to discover the reservoir of EBOVs [ 32 ] including the 1976 first recorded DRC outbreaks and Sudan, the 1979 outbreak in DRC in 1979 and 1995 following the Kikwit outbreak, the same year in the Tai Forest and in 1999 in the Central African Republic [ 33 , 34 , 35 , 36 , 37 , 38 ] . A total of more than 7000 vertebrates and 30,000 invertebrates were sampled and tested for the presence of EBOVs. Limited finding was inconclusive for an potential EBOVs reservoir status among all these animals. Moreover, while several animal species (Bats, birds, reptiles, mollusks, arthropods, and plants) were experimentally infected with ZEBOV, only two fruit bat species ( Epomophorus spp. and Tadarida spp.) developed a subclinical transient viremia [ 39 ]. If these results were not confirmed in the natural settings, they indicated the potential for chiropteran to be natural for EBOVs [ 40 ].

Also, historically, the first documented case of EVD in Sudan in 1976, the index case was located (by the World Health Organization) in a cotton factory far from the forest block, where the only wild significantly abundant species was an insectivorous bat species [ 21 ].

Since the discovery of EBOV in 1976, more than half of the epidemic outbreaks caused by EBOVs have broken down between Gabon and the DRC. Following the successive EBOV outbreaks in Gabon from 1995 to 2001 affecting several animal species non-human primates, and wild ungulates and responsible of the dramatic decline of great apes (gorilla and chimpanzee) populations in the region (Leroy et al. [ 16 ]), researchers engaged several missions of captures of wild animals in the forest areas affected by the recent past epidemics. Also, 1030 animals were captured and analyzed, only three species of fruit bats were found infected with the ZEBOV by PCR including: Hypsignathus monstrosus ; Epomops franqueti; and Myonycteris torquata . Moreover, antibody reacting anti-Ebola were detected in these species as well as for the genus Myonycteris spp. leading ultimately to design Chiropteran as a potential reservoir of EBOVs [ 41 ].

Since then, many studies have converged in favor of the role of chiropters in maintaining EBOV in the wild (Caron et al. [ 42 ], Leendertz). In addition, a recent study of bats in Sierra Leone showed the association of an EBOV like with several species of bats ( Mops condylurus and Chaerephon pumilus ) from the Molossus family [ 43 ]. Moreover, a potential direct exposure to Ebola infected fruit bats was also reported as a putative index case of large epidemics [ 44 , 45 ]. Moreover, further studies reported on direct infection of natural hosts (primates) by EBOV infected bats as highly plausible, given that bats, especially fruit bats, are frequently hunted and consumed as bushmeat by human when Cercopithecus species hunt roosting bats for consumption [ 46 ] also preying on bats has been reported in Cercopithecus ascanius and C. mitis (East Africa) as well as bonobos (DRC) [ 47 ]. It is also possible that different modes of exposure to Ebola virus could lead to different antibody profiles, that is, contaminated fruit vs. contact with infected bats during hunting [ 44 , 47 , 48 ].

Altogether, several fruit bats ( Epomophorus wahlbergi ) and insectivorous bats ( Chaerephon pumilus, Mops condylurus ) experimentally survive to EBOV infections [ 39 ], EBOV RNA and/or anti EBOV reacting antibodies were detected also in several other fruit bat species ( Epomops franqueti, Hypsignathus monstrosus, Myonycteris torquata , Eidolon helvum, Epomophorus gambianus, Micropteropus pusillus, Mops condylurus, Rousettus aegyptiacus, Rousettus leschenaultia ) giving more insight of the potential for chiropteran to be a potential host or reservoir host of EBOVs [ 22 , 49 , 50 ].

Interestingly, REBOV was also found associated with the bats in its natural habitat of the Philippines [ 51 ]. Also, again in this same Filoviridae family, Marburg viruses in Africa are clearly associated with bats [ 32 , 52 ] as well as the Cueva virus in Europe [ 53 ]. While REBOV has been find associated with fruit bats, Roussetus spp. (Pteropodid family), each filovirus genus is associated with a specific chiropteran group including: Marburgvirus with a specific fruit bat, Roussetus aegyptiacus (Pteropodid family); and Cuevavirus with insectivorous bat, Miniopterus schreibersii (Miniopterid family); except for Thamnovirus isolated form fresh water fish.

Moreover, several virus groups are known to hold bat-borne viruses including the coronaviruses, hantaviruses, lyssaviruses, lassa virus, Henipavirus, filovirus which are among the most severe of the emerging viruses [ 54 , 55 ].

Conclusively, this was the first evidence of chiropteran as a potential reservoir and/or vector of EBOV, while several wild animals, in particular great apes were find highly sensitive to EBOV infection. Also, if several species of chiropteran have been identified as a potential virus reservoir,

4.2 The most complete figure of a putative Ebolavirus natural cycle in the central African raining forest

From all above observations, records and historical events of EBOVs emerging events, several fundamentals of emergence have been identified as well putative time and space of such events where, that is when the virus jump from the cryptic natural cycle of the reservoir-vector to manifest itself clearly as an open index case of infection in a susceptible host and the potential opening epizootic or epidemic chain.

4.2.1 The actors

Again, from the literature numerous vertebrates appears to be permissive to infection by EBOVs, however, due to their ethology, including environmental habits, societal structure, density and their ability of intra and interspecies to mingle. Altogether primates appear highly susceptible to EBOVs infection including non-human primate apes, gorilla and chimpanzee, but also cercopithecids (e.g. colobus) but also small wild ungulates (e.g. forest duikers) and eventually domestic animals (e.g. dogs) [ 32 , 56 , 57 , 58 ].

One can summarize that EBOVs natural hosts belongs to chiropteran as a potential host reservoir represented mostly by Pteropodidae in Africa (REBOV and Roussetus; Bombali virus and Molossidae), and as secondary natural or accidental wild and domestic hosts including several other mammals: primates (Colobus, Cercopithecus), non-human primates (Gorilla, chimpanzee), wild ungulates (duikers) and, human primates. Also this needs to be taken into account with respect to other permissive species to EBOVs, indeed, as an example, if Roussetus spp. was shown to carry EBOVs reacting antibodies more recently R. aegyptiacus bats were demonstrated to unlikely able to maintain and perpetuate EBOV in nature while the natural transmission of filovirus in R. aegyptiacus , resulting viral replication and shedding are unknown [ 59 ].

4.2.2 The stages

The African Rain forest of the Congolese basin appears to be the epicenter of EBOVs emerging events. More than 80% of the emerging events of EBOVs occurred in the Tropical zone under the influence of the (Intertropical converging zone, ITCZ) from five degree North to 5 degrees south and oscillating as much as 40 to 45° of latitude north or south of the equator based on the pattern of land and ocean beneath it [ 28 ] ( Figure 2 ).

Emerging events of Ebolavirus and climate since the Ebola fever inception in Africa. Left = annual rainfall; right = annual temperature. To illustrate the association temperature/rainfall and emergence, the month of May was chosen because it is at this time of the year that we observe the most emergent events of the Ebola virus. Temperature and rainfall are expressed as an annual average for the period under consideration. The precise location of 32 Ebola emergent events are here integrated into the global climatic map of Africa. Only 30-year average values per month of rainfall are available for the study period (ref.: WorldClim world databases) as well for the average monthly temperature.

Temperature and precipitation data for Africa (average data computed from 1960 to 1990, 300 m resolution [HIJ 05]) were integrated with the distribution map of the emergent events of the Ebola virus and the values ​​calculated for each of the emergence points [ 60 ].

On all emergence points, the temperature at the time of emergence is not significantly different from the average annual temperature over 30 years. The difference in temperature between the moment of emergence and the average temperature (of 30 years monthly average) of the hottest month does not show any difference either. Emergence would not be directly related to temperature.

When we compare Ebolavirus emerging events time and the rainfall, there is strict quantitative correlation between rainfall and emergence: Most of the emergent events (93.8%) occurred during the rainy season ( Figure 2 ). For precipitation values, there is a slightly statistically significant (p = 0.02) positive difference between the average precipitation of the month of emergence and the average of the monthly average precipitation (over 30 years), indicating that precipitations are higher when emergences occur. There is an even more statistically significant (p = 0.003) positive difference when considering precipitation of the month preceding the emergence. Emergence is therefore likely to be associated with rainfall intensity and the rainy season. 10/32 emergences occur at the beginning of the rainy season, 9/32 in the middle, and 11/32 at the end. Only 2/32 emergences occurred in the dry season.

When referring to land use ( Figure 3 ) the temperature at the 6 emergence points in “Cropland” is highly significantly less (p = 0.005) than 15% (21.6°C) at temperature (24.4°C) to the 9 points in “Tree cover, broadleaved, evergreen, closed to open”, however the average temperature of the Cropland (21.6°) is to a degree less, significantly lower (p = 0.01) than that of the “Tree cover” (24.5°C).

Environmental factors surrounding Ebolavirus emerging event: Land use and places of Ebola virus emergence in Africa from 1976 to 2014. Land use from ESA 2015, 300 m resolution; red circle = putative place of the Ebola virus emergence (index case). Estimated Ebola emergence places are superimposed on the land use layer. The identification of the land use types were 32 points (red circle) representing the putative places of Ebolavirus emergence are superimposed and are distributed as follows: (1) cropland: 6, (2) herbaceous cover: 5, (3) cropland mosaic: 5 (> 50% natural vegetation vs. <50% tree, shrub, herbaceous cover), (4) tree cover with: (a) 15% of broadleaved, evergreen, closed to open: 9, (b) 15–40% of broadleaved, deciduous, open: 2, (5) flooded, fresh or brackish water: 1, (6) urban areas: 3, and (7) water bodies: 1. The limitations of this interpretation are linked to the accuracy of the location of Ebolavirus emergence sites (from literature and reports) and, to the evolution of vegetation cover over the past decades since the first emergence of the Ebolavirus occurred in Africa.

Ultimately, taking into account these environmental factors, when we look for an association between the emergent events of the Ebola virus and the characteristics of the places of these emergences (i.e. land use, temperature, rainfall) it turns out that the emergences are always in the zone of heavy rainfall, but nevertheless do not follow the moving of the rainy season. Moreover, these emergences remain always and remarkably close enough to the Equator, therefore in the equatorial forest area with a high hygrometry, and a moderate annual temperature. However, the temperature at the time of emergence is not significantly different from the average annual temperature (at the points of emergence) which does not allow to distinguish seasonal effect in the emergence-temperature relationship. Conclusively, we did not identify a seasonality associated with the time of emergence, however the emerging events occur in specific geographic zone characterized by several environmental factors. Finally, the emergence zones are in areas of Land Use with specific temperatures not related to seasonality. Ultimately, it is also remarkable that all these emerging events occurred in an area with a highly potential presence of apes, virus-sensitive hosts.

4.2.3 Fundamentals and domains of emergence: a theory for a natural cycle of EBOVs in Africa

Also, the EBOVs species are closely genetically related, their seems to occur by foci in nature. The host appears to be the same, natural or accidental, and the transmission done by direct contact with infected hosts or its biological products [ 50 , 61 ]. Altogether, in the early 2000s, before the identification of chiropteran as a potential host-reservoir of the EBOVs, a hypothetic natural cycle was described empirically based on seasonal environmental climatic factors [ 55 ]. Then, taking into account bats as a potential reservoir-host, the question of virus transmission was central to consider while environmental factors appears to play a major role to the host and their natural cycle (Chiropteran physiology) (climate/fructification, chorology, bats physiology). Several factors of emergence were then listed including: Chronic infection, infected organs, virus shedding, close encounters between reservoir and susceptible hosts, food and water resource, seasonality, chorology (i.e. causal effect between geographical phenomena – season) in the tropical rain forest and the spatial distribution of chiropteran (i.e. index site of Ebola emerging events).

Epidemiological field surveys indicate that mass mortalities of apes and monkey species due to Ebola virus often appear at the end of the dry season, a period when food resources are scarce. Restricted access to a limited number of fruit-bearing trees can lead to spatiotemporal clustering of diverse species of frugivorous animals, such as bats, nonhuman primates, and other terrestrial species foraging on fallen partially eaten (by bats) fruits. These aggregates of wild animal species favor the contact between infected and susceptible individuals and promote virus transmission. The dry season aggregation of reservoir host species involved in natural maintenance cycles, augmented by incidentally infected secondary hosts serving as sources for intra- and interspecific transmission chains independent of repeated spillover from the reservoir host, provides an ecological setting for amplifying enzootic transmission of Ebola virus when a vertebrate hosts are concentrated around a scarce number of water sources [ 62 ].

In addition to this dietary impoverishment, there are behavioral and physiological events occurring among bats during the tropical dry favor the contact frequency and intimacy between bats, which can promote transmission of Ebola virus to others and increase R0. As an example, megachiropteran fruit bats breeding activities and intraspecific competitions between males and grouped kidding of females favor the contact between individuals. Moreover, pregnancy can involve physiological changes among female bats that alter immune functions and eventually favor virus shedding. Parturition among the African megachiropteran bats occurs throughout the year, although seasonal peaks provide birthing fluids, blood, and placental tissues, potentially Ebolavirus infected, falling on the ground as a medium highly attractive and readily available to scavenging terrestrial mammals [ 50 , 56 , 63 ] ( Figure 4A and B ).

(A) Understanding Ebolavirus enzootic and epidemics. Red arrows = cycles of transmission; dashed square = a putative natural cycle of Ebolavirus in Central Africa (see B). Fruit bats are considered to be a putative reservoir of Ebola virus in Central Africa after 2004; In 2009, several non-human primate epizootic are reported; 1976 was the first emerging events and subsequent epidemic chains in remote area of the rain forest and close by; 2012 showed a dramatic spread of the virus associated with motorized transportation and ground network; In 2014 urban epidemics are reported as well as a pandemic risk and become an international public health emergency. (B) Putative natural cycle of Ebolavirus in Central Africa. Red arrow indicates Ebolavirus transmission. Numbered red circle of transmission: (1) sylvatic inter- and intra-species transmission; (2) chiropteran migration; (3) chiropter to primate (close contact of dejection); (4) primate inter species (Cercopithecus/chimpanzee); (5) primate to primate (non-human primates); (6) non-human primate epizootic (gorillas); (7) chiropter to duikers; and (8) consumption of chiropteran infected food by shrew or wild pig.

5. If we had to conclude

Based on historical data and observations, the presented hypothesis of the natural cycle of Ebolavirus emergence prevail an inter-species spillover as the complex natural cycle involving several hosts (reservoir, vector, amplifier), as well as biotic and abiotic factors in a changing environment among other original features.

Although the natural cycle of EBOVs remains in the darkness of the rain forest, strong findings and comparative analysis of close parents of the filovirus throw some light to a potential natural cycle of EBOVs in Africa. EBOVs clearly appear linked to chiropteran and dependent for merging events in the environmental factors. Indeed, it appears that filoviridae are often associated with chiropteran while the emergence of the virus strains occurs as a sparse focus with a silent period of cryptic virus circulation. When virus transmission, i.e. spillover, from a hidden natural cycle, to accidental hosts occurs, it happened in a specific time-frame often linked to the season.

One can retain is that the EBOVs complex natural cycle is yet not on entirely elucidated and certainly dependent on environmental factors – associated with a specific environment of the chiropteran species incriminated (i.e. Different territories, different cycle) - leading to multiple, sometime concurrent, temporally and timely emergence in focus.

Although, other hypothesis has been suggested elsewhere including the Ebola virus Disease as an arthropod borne disease among others [ 42 ], there is important fundamental matters to consider as well before providing more.

However, beyond these hypotheses, fundamental questions subsist in order to go further learn. We can cite in particular the mystery of kin between the Reston virus of Asia and the Ebola viruses of Africa, would there not be a missing link in a geographic area yet to discover. Do the filovirus exist in the Americas hidden in the darkness of the tropical forest? Also, the Ebolavirus seems genetically stable, related to particular species of chiropter, was it to think about a co-evolution of the host and the virus in this closed environment of the forest of the tropical? Today, with the endless epidemic unfolding in the DRC, should we revisit our tools and strategy of struggle in an ever-changing world? [ 64 ].

Acknowledgments

We sincerely thank for their supports, brings to all the authors of this deep and never-ending research and scientific thought around an outstanding and fascinating subject: Georgetown University, Centaurus Biotech LLC., The DHS Emeritus Center for Emerging Zoonotic and Animal Diseases at Kansas State University.

Conflict of interest

All authors do not have any conflict of interest whatsoever with this published manuscript.

• 1. CDC. Page last reviewed. Content source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of High-Consequence Pathogens and Pathology (DHCPP), Viral Special Pathogens Branch (VSPB). 2019. Available from: https://www.cdc.gov/vhf/ebola/history/2014-2016-outbreak/index.html
• 2. ICTV. Filoviridae. 2019. Available from: https://talk.ictvonline.org/ictv-reports/ictv_online_report/negative-sense-rna-viruses/mononegavirales/w/filoviridae
• 3. Kuhn JH, Andersen KG, Baize S, Bào Y, Bavari S, Berthet N, et al. Nomenclature- and database-compatible names for the two Ebola virus variants that emerged in Guinea and the Democratic Republic of the Congo in 2014. Viruses. 2014; 6 (11):4760-4799. DOI: 10.3390/v6114760
• 4. MacNeil A, Farnon EC, Morgan OW, et al. Filovirus outbreak detection and surveillance: Lessons from Bundibugyo. The Journal of Infectious Diseases. 2011; 204 :S761-S767
• 5. Kiley MP, Bowen ET, Eddy GA, Isaäcson M, Johnson KM, McCormick JB, et al. Filoviridae: A taxonomic home for Marburg and Ebola viruses? Intervirology. 1982; 18 (1-2):24-32
• 6. Anonymous. WHO/INTERNATIONAL STUDY TEAM. Ebola haemorrhagic fever in Zaire, 1976. Bulletin of the World Health Organization. 1978; 56 (2):271-293
• 7. Anonymous. WHO/INTERNATIONAL STUDY TEAM. Ebola haemorrhagic fever in Sudan, 1976. Bulletin of the World Health Organization. 1978; 56 (2):247-270
• 8. Centers for Disease Control. Ebola-Reston virus infection among quarantined nonhuman primates–Texas, 1996. Morbidity and Mortality Weekly Report. 1996; 45 :314-316
• 9. Miranda MEG, Lee N, Miranda J. Reston ebolavirus in humans and animals in the Philippines: A review. The Journal of Infectious Diseases. 2011; 204 (suppl_3):S757-S760. DOI: 10.1093/infdis/jir296
• 10. Le Guenno B, Formenty P, Wyers M, Gounon P, Walker F, Boesch C. Isolation and partial characterisation of a new strain of Ebola virus. The Lancet. 1995; 345 (8960):1271-1274
• 11. Towner JS, Sealy TK, Khristova ML, Albariño CG, Conlan S, Reeder SA, et al. Newly discovered ebola virus associated with hemorrhagic fever outbreak in Uganda. PLoS Pathogens. 2008; 4 (11):e1000212. DOI: 10.1371/journal.ppat.1000212
• 12. Miranda ME, Ksiazek TG, Retuya TJ, Khan AS, Sanchez A, Fulhorst CF, et al. Epidemiology of Ebola (subtype Reston) virus in the Philippines, 1996. The Journal of Infectious Diseases. 1999; 179 (Suppl 1):S115-S119
• 13. Georges AJ, Leroy EM, Renaud AA, et al. Ebola hemorrhagic fever outbreaks in Gabon, 1994-1997: Epidemiologic and health control issues. The Journal of Infectious Diseases. 1999; 179 :S65-S75
• 14. Baize S, Pannetier D, Oestereich L, Rieger T, Koivogui L, Magassouba N, et al. Emergence of Zaire Ebola virus disease in Guinea. The New England Journal of Medicine. 2014; 371 (15):1418-1425. DOI: 10.1056/NEJMoa1404505
• 15. WHO. Disease Outbreak News. 2018a. Available from: https://www.who.int/ebola/situation-reports/drc-2018/en/ [Accessed: 13-01-19]
• 16. Leroy EM, Rouquet P, Formenty P, Souquiere S, Kilbourne A, Froment JM, et al. Multiple Ebola virus transmission events and rapid decline of central African wildlife. Science. 2004a; 303 :387-390
• 17. Heymann DL, Weisfeld JS, Webb PA, Johnson KM, Cairns T, Berquist H. Ebola hemorrhagic fever: Tandala, Zaire, 1977-1978. The Journal of Infectious Diseases. 1980; 142 :372-376
• 18. O’Hearn AE, Voorhees MA, Fetterer DP, Wauquier N, Coomber MR, Bangura J, et al. Serosurveillance of viral pathogens circulating in West Africa. Virology Journal. 2016; 13 (1):163
• 19. Becquart P, Wauquier N, Mahlakõiv T, Nkoghe D, Padilla C, Souris M, et al. High prevalence of both humoral and cellular immunity to Zaire ebolavirus among rural populations in Gabon. PLoS One. 2010; 5 (2):e9126
• 20. Vincent T. Ebola Footprint—Broader Than You Think. Available from: http://oneill.law.georgetown.edu/the-ebola-footprint-broader-than-you-think/
• 21. Olivero J, Fa JE, Real R, Farfan MA, Marquez AN, Vargas JM, et al. Mammalian biogeography and the Ebola virus in Africa. Mammal Review. 2016; 47 :24-37
• 22. Olival KJ, Islam A, Yu M, Anthony SJ, Epstein JH, Khan SA, et al. Ebola virus antibodies in fruit bats, Bangladesh. Emerging Infectious Diseases. 2013; 19 :270-273. DOI: 10.3201/eid1902.120524
• 23. Yuan JF, Zhang YJ, Li JL, Zhang YZ, Wang LF, Shi ZL. Serological evidence of ebolavirus infection in bats, China. Virology Journal. 2012; 9 :236. DOI: 10.1186/1743-422X-9-236
• 24. Peterson AT, Bauer JT, Mills JN. Ecologic and geographic distribution of filovirus disease. Emerging Infectious Diseases. 2004; 10 :40-47. DOI: 10.3201/eid1001.030125
• 25. Rollin PE, Williams RJ, Bressler DS, Pearson S, Cottingham M, Pucak G, et al. Ebola (subtype Reston) virus among quarantined nonhuman primates recently imported from the Philippines to the United States. The Journal of Infectious Diseases. 1999; 179 (Suppl 1):S108-S114
• 26. Wauquier N, Bangura J, Moses L, Humarr Khan S, Coomber M, Lungay V, et al. Understanding the emergence of ebola virus disease in Sierra Leone: Stalking the virus in the threatening wake of emergence. PLOS Currents. 2015; 7
• 27. Ebola virus cases in the United States. Available from: https://en.wikipedia.org/wiki/Ebola_virus_cases_in_the_United_States
• 28. Monath TP. Ecology of Marburg and Ebola viruses: Speculations and directions for the future research. The Journal of Infectious Diseases. 1999; 179 :S127-S138
• 29. Yob JM, Field H, Rashdi AM, Morrissy C, van der Heide B, Rota P, et al. Nipah virus infection in bats (order Chiroptera) in peninsular Malaysia. Emerging Infectious Diseases. 2001; 7 (3):439-441
• 30. Badrane H, Tordo N. Host switching in Lyssavirus history from the Chiroptera to the Carnivora orders. Journal of Virology. 2001; 75 :8096-8104
• 31. Tom Vincent. EBOLA: FIFTEEN YEARS OF SILENCE. 2019. Available from: http://oneill.law.georgetown.edu/ebola-fifteen-years-of-silence/
• 32. Pourrut X, Souris M, Towner JS, Rollin PE, Nichol ST, Gonzalez JP, et al. Large serological survey showing cocirculation of Ebola and Marburg viruses in Gabonese bat populations, and a high seroprevalence of both viruses in Rousettus aegyptiacus. BMC Infectious Diseases. 2009; 9 :159
• 33. Breman JG, Johnson KM, van der Groen G, Robbins CB, Szczeniowski MV, Ruti K, et al. A search for Ebola virus in animals in the Democratic Republic of the Congo and Cameroon: Ecologic, virologic, and sero- logic surveys, 1979-1980. The Journal of Infectious Diseases. 1999; 179 :S139-S147
• 34. Arata AA, Johnson B. Approaches towards studies on potential reservoirs of viral haemorrhagic fever in southern Sudan. In: Pattyn SR, editor. Ebola Virus Haemor- Rhagic Fever. Amsterdam: Elsevier/Netherland biomedical; 1977. pp. 191-202
• 35. Leirs H, Mills JN, Krebs JW, Childs JE, Akaibe D, Woollen N, et al. Search for the Ebola virus reservoir in Kikwit Democratic Republic of the Congo: Reflections on a vertebrate collection. The Journal of Infectious Diseases. 1999; 179 :S155-S163
• 36. Morvan JM, Deubel V, Gounon P, Nakoune E, Barriere P, Murri S, et al. Identification of Ebola virus sequences present as RNA or DNA in organs of terrestrial small mammals of the Central African Republic. Microbes and Infection. 1999; 1 :1193-1201
• 37. Reiter P, Turell M, Coleman R, Miller B, Maupin G, Liz J, et al. Field investigations of an outbreak of Ebola hemorrhagic fever Kikwit Democratic Republic of the Congo, 1995: Arthropod studies. The Journal of Infectious Diseases. 1999; 179 :S148-S154
• 38. Formenty P, Boesch C, Wyers M, Steiner C, Donati F, Dind F, Walker F, Le Guenno B. Ebola virus outbreak among wild chimpanzees living in a rain forest of cote d’Ivoire. The Journal of Infectious Diseases. 1999; 179 (Suppl 1):S120-S126
• 39. Swanepoel R, Leman PA, Burt FJ. Experimental inoculation of plants and animals with Ebola virus. Emerging Infectious Diseases. 1996; 2 :321-325
• 40. Xavier P, Gonzalez JP, Leroy E. Spatial and temporal patterns of Ebola virus antibody prevalence in the putative bat species reservoir. The Journal of Infectious Diseases. 2007; 196 (Suppl 2):S176-S183
• 41. Eric L, Kumulungui B, Pourrut X, Rouquet P, Yaba P, Délicat A, et al. Fruit bats as reservoirs of Ebola virus. Nature. 2005; 438 (7068):575-576
• 42. Caron A, Bourgarel M, Cappelle J, Liégeois F, De Nys HM, Roger F. Ebola virus maintenance: If not (only) bats, what Else? Viruses. 2018; 10 (10):549. DOI: 10.3390/v10100549
• 43. Goldstein T, Anthony SJ, Gbakima A, Bird BH, Bangura J, Tremeau-Bravard A, et al. The discovery of Bombali virus adds further support for bats as hosts of ebolaviruses. Nature Microbiology. 2018; 3 :1084-1089
• 44. Leroy EM, Epelboin A, Mondonge V, Pourrut X, Gonzalez JP, Muyembe-Tamfum JJ, et al. Ebola outbreak associated with direct exposure to fruit bats in Luebo, Democratic Republic of the Congo, 2007. Vector Borne and Zoonotic Diseases. 2009; 9 (6):723-728
• 45. Marí Saéz A, Weiss S, Nowak K, Lapeyre V, Zimmermann F, Düx A, et al. Investigating the zoonotic origin of the west African Ebola epidemic. EMBO Molecular Medicine. 2015; 7 (1):17-23. DOI: 10.15252/emmm.201404792
• 46. Tapanes E, Detwiler KM, Cords M. Bat predation by Cercopithecus monkeys: Implications for zoonotic disease transmission. EcoHealth. 2016; 13 :405-409
• 47. Bermejo M, Illera G, Sabater P. Animals and mushrooms consumed by bonobos (pan paniscus): New records from Lilungu (Ikele), Zaire. International Journal of Primatology. 1994; 15 :879-898
• 48. Leendertz SAJ, Gogarten JF, Düx A, Calvignac-Spencer S, Leendertz FH. Assessing the evidence supporting fruit bats as the primary reservoirs for Ebola viruses. EcoHealth. 2016; 13 (1):18-25
• 49. Olival KJ, Hayman DT. Filoviruses in bats: Current knowledge and future directions. Viruses. 2014; 6 (4):1759-1788. DOI: 10.3390/v6041759
• 50. Gonzalez JP, Pourrut X, Leroy E. Ebolavirus and other filoviruses. Current Topics in Microbiology and Immunology. 2007; 315 :363-387
• 51. Jayme SI, Field HE, de Jong C, Olival KJ, Marsh G, Tagtag AM, et al. Molecular evidence of Ebola Reston virus infection in Philippine bats. Virology Journal. 2015; 12 :107. DOI: 10.1186/s12985-015-0331-3
• 52. Pawęska JT, Jansen van Vuren P, Kemp A, Storm N, Grobbelaar AA, Wiley MR, et al. Marburg virus infection in Egyptian Rousette bats, South Africa, 2013-20141. Emerging Infectious Diseases. 2018 Jun; 24 (6):1134-1137. DOI: 10.3201/eid2406.172165
• 53. de Arellano ER, Sanchez-Lockhart M, Perteguer MJ, Bartlett M, Ortiz M, Campioli P, et al. First evidence of antibodies against Lloviu virus in Schreiber’s bent-winged insectivorous bats demonstrate a wide circulation of the virus in Spain. Viruses. 2019; 11 :360. DOI: 10.3390/v11040360
• 54. Calisher CH, Childs JE, Field HE, Holmes KV, Schountz T. Bats: Important reservoir hosts of emerging viruses. Clinical Microbiology Reviews. 2006; 19 :531-545
• 55. Gonzalez JP, Pourrut X, Leroy E. Ebolavirus and other filoviruses. In: Childs JE, Mackenzie JS, Richt JA, editors. Wildlife and Emerging Zoonotic Diseases: The Biology, Circumstances and Consequences of Cross-Species Transmission. New York, NY, USA: Springer; Heidelberg, Germany; 2007. pp. 363-388
• 56. Allela L, Bourry O, Pouillot R, Délicat A, Yaba P, Kumulungui B, et al. Ebola virus antibody in dogs and human risk. Emerging Infectious Diseases. 2005; 11 (3):385-390
• 57. Ayouba A, Ahuka-Mundeke S, Butel C, Mbala Kingebeni P, Loul S, Tagg N, et al. Extensive serological survey of multiple African non-human primate species reveals low prevalence of IgG antibodies to four Ebola virus species. The Journal of Infectious Diseases. 2019. DOI: 10.1093/infdis/jiz006
• 58. Pigott DM, Golding N, Mylne A, et al. Mapping the zoonotic niche of Ebola virus disease in Africa. eLife. 2014; 3 :e04395
• 59. Paweska JT, Storm N, Grobbelaar AA, Markotter W, Kemp A, Jansen van Vuren P. Experimental inoculation of Egyptian fruit bats ( Rousettus aegyptiacus ) with Ebola virus. Viruses. 2016; 8 (2). pii: E29. DOI: 10.3390/v8020029
• 60. Hijmans RJ, Cameron SE, Parra JL, Jones PG, Jarvis A. Very high-resolution interpolated climate surfaces for global land areas. International Journal of Climatology. 2005; 25 :1965-1978
• 61. Mackensie J, Mills J, editors. Review. In: Wildlife and Emerging Zoonotic Diseases. Springer-Verelag CRC Press. Advances in Virology ch20
• 62. Shaman J, Day JF, Stieglitz M. Drought-induced amplification of Saint Louis encephalitis virus Florida. Emerging Infectious Diseases. 2002; 8 :575-580
• 63. Pourrut X, Kumulungui B, Wittmann T, Moussavou G, Delicat A, Yaba P, et al. The natural history of Ebola virus in Africa. Microbes and Infection. 2005; 7 (7-8):1005-1014
• 64. Gonzalez JP, Souris M, Valdivia-Granda W. Global spread of hemorrhagic fever viruses: Predicting pandemics. Methods in Molecular Biology. 2018; 1604 :3-31. DOI: 10.1007/978-1-4939-6981-4_1

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3.0 License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Continue reading from the same book

Edited by Samuel Okware

Published: 12 February 2020

By David A. Schwartz

1238 downloads

By Felix B. He, Krister Melén, Laura Kakkola and Ilkk...

1439 downloads

By Oumar Faye, Cheikh Tidiane Diagne, Amadou Diallo, ...

769 downloads

Home — Essay Samples — Nursing & Health — Infectious Diseases — Ebola Virus

Essays About Ebola Virus

Ebola virus essay topics and outline examples, essay title 1: unmasking ebola: origins, transmission, and global response.

Thesis Statement: This essay provides an in-depth analysis of the Ebola virus, including its origins, modes of transmission, symptoms, and the global efforts in containing and managing Ebola outbreaks.

• Introduction
• Understanding Ebola: History, Types, and the Zaire Ebola Virus
• Transmission and Symptoms: How Ebola Spreads and Its Impact on the Human Body
• Outbreaks and Epidemics: Notable Ebola Outbreaks and Their Consequences
• Global Response: International Organizations, Research, and Medical Interventions
• Lessons Learned: Preparing for Future Ebola Outbreaks and Emerging Diseases
• Conclusion: The Ongoing Battle Against Ebola and Infectious Disease Preparedness

Essay Title 2: Ebola's Socioeconomic Impact: Health Systems, Communities, and Resilience

Thesis Statement: This essay explores the broader socioeconomic implications of Ebola outbreaks, examining their impact on healthcare systems, affected communities, and the resilience strategies employed in response to the crisis.

• Healthcare Infrastructure: Vulnerabilities and Challenges During Ebola Outbreaks
• Community Resilience: Coping Strategies and Local Responses to Ebola
• Economic Consequences: Impact on Livelihoods, Trade, and Economic Stability
• Psychosocial Effects: Stigma, Trauma, and Mental Health Considerations
• Global Aid and Assistance: International Support for Affected Regions
• Recovery and Rebuilding: Post-Ebola Rehabilitation and Strengthening Systems
• Conclusion: Beyond the Epidemic - Long-term Recovery and Strengthening Resilience

Essay Title 3: Ebola Vaccines and Therapeutics: Advances, Challenges, and Future Prospects

Thesis Statement: This essay delves into the development of Ebola vaccines and therapeutics, discussing recent advancements, challenges in deployment, and the potential for future innovations in combating Ebola.

• The Race for a Vaccine: Historical Context and the Quest for Immunization
• Therapeutics and Treatment: Experimental Drugs, Blood Plasma, and Supportive Care
• Vaccine Development: Progress in Vaccine Trials and Their Efficacy
• Challenges in Deployment: Ethical Considerations, Access, and Distribution
• Future Prospects: Potential Innovations in Ebola Prevention and Treatment
• Global Health Security: Ebola Preparedness and Pandemic Response
• Conclusion: Advancing Science and Preparedness in the Fight Against Ebola

Evaluation of The Issues Related to The Ebola Virus

Assessment of the ebola virus as a severe problem and ways to stop the disease, made-to-order essay as fast as you need it.

Each essay is customized to cater to your unique preferences

+ experts online

Review on African Virus Ebola

The main problems and suggestions regarding the spread of the ebola disease in africa, the importance of community engagement in eradication of the ebola virus, let us write you an essay from scratch.

• 450+ experts on 30 subjects ready to help
• Custom essay delivered in as few as 3 hours

Relevant topics

• Yellow Fever
• Dengue Fever

By clicking “Check Writers’ Offers”, you agree to our terms of service and privacy policy . We’ll occasionally send you promo and account related email

No need to pay just yet!

We use cookies to personalyze your web-site experience. By continuing we’ll assume you board with our cookie policy .

• Instructions Followed To The Letter
• Deadlines Met At Every Stage
• Unique And Plagiarism Free

Can I pay after you write my essay for me?

Sharing Educational Goals

Our cheap essay service is a helping hand for those who want to reach academic success and have the perfect 4.0 GPA. Whatever kind of help you need, we will give it to you.

• How it Works
• Top Writers

an expository essay on ebola virus

Expository Essay on Ebola Virus

Jump ahead to:

Here you have an Expository Essay on Ebola Virus, Lets start with the introduction.

• Introduction

The Ebola virus is one of the most dangerous and deadly viruses known to humans. The Ebola epidemic since its discovery in 1976 came from the Democratic Republic of Congo, formerly known as Zaire, but the largest Ebola outbreak known to date is still ongoing at the time of writing, in the West Africa. An estimated 550 000 reported incidents from Sierra Leone and Liberia took place on January 20, 2015.

The virus is prevalent in many countries including Guinea, Liberia, Sierra Leone, Nigeria as well as occasional reported cases in the USA, Canada. The Netherlands and India show the potential for infection to spread globally. Despite the fact that the disease is highly contagious, life-threatening, and no specific treatment is available, it can be prevented through the use of appropriate measures to prevent and control infection. The study of the Ebola virus is important as such knowledge will pave the way for the reduction of victims, the development of an effective drug and will be useful in controlling the same epidemic.

The Ebola virus is a member of the Philoviridae family. As the name implies the virus has a filamentous shape. Marburg virus and Ebolavirus are two major generations of the virus family that are important in medicine. Bacteria of these two species are studied and presented together due to their many similarities in the life cycle, water storage areas, transmission methods, clinical presentation, treatment and prevention measures. The only difference is that Marburgvirus is still distributed by forest-dwelling bats such as the savannah while Ebolavirus is distributed by bats species accustomed to deep rain forests.

Five subspecies of Ebolavirus, namely, Ebolavirus Zaire, Ebolavirus Sudan, Ebolavirus reston, Ebolavirus cote d’Ivore, and Ebolavirus bugs, have been identified and named after the place where they were first discovered. Of these E. Zaire was the first to be isolated and studied and is responsible for a large number of outbreaks  including recent outbreaks in 2014 before that E. Sudan accounted for ¼ of all Ebolavirus deaths. With the exception of a slightly lower mortality rate, E. Sudan is almost identical to E. Zaire. E death rate of E case. Sudan is reported as 40-60% and E. Zaire as 60-90%.

Ebola was originally transmitted to humans as a zoonosis. Different species of bats are found throughout sub-Saharan Africa such as. Contact with bats by biting and scratching or exposure to their discharges and discharges through broken skin or mucous membranes can cause infection in humans. The infection can also be spread to other end users. Those recorded in Africa are deer, wildebeests, chimpanzees, chimpanzees, gorillas, monkeys, and other non-humans. Attacks during the hunting of these animals or handling carcasses of infected animals have led to the introduction of the virus to humans from the wild. Outbreaks appear to be exacerbated during pregnancy and in childbirth. Records show that outbreaks appear to be exacerbated by the presence of multiple pathogens.

EVD is highly contagious. Infection can be spread in the community and in a hospital setting by direct contact with infected body fluids such as blood, fluid and discharge or the patient’s tissues or by direct contact with contaminants such as clothing and bed linen. One of the main reasons for the rapid spread of the epidemic is traditional funeral rites, which include cadaver cleaning, removal of fingernails, toenails and clothing. Caregivers, including health workers, are also at greater risk of contracting the disease. In addition the sperm of the surviving male is said to remain infected for up to 82 days after the onset of symptoms. As long as the virus stays in the body fluids a person stays infected. The spread of the Ebola virus is highly suspected but has not been proven by experiments.

Clinical Introduction

EVD caused by different types of Ebola virus brings different clinical features. The incubation period of Ebola virus is generally considered to be 2 – 21 days. Ebola virus disease shows a variety of symptoms that develop deep in the prodromal constitution leading to various diagnoses including not only other viral hemorrhagic diseases, but also malaria, typhoid, cholera, and others. bacterial rickettsia and non-infectious causes of bleeding.

The onset of the disease is similar to that of severe hemorrhagic fever. Patients have high fever, fever reaching 39-400C, body aches and fatigue. Subsequent abdominal symptoms such as epigastric pain, vomiting and / or bloodless diarrhea appear if the fever persists throughout the day. 3-5.

After 4 – 5 days of illness macular degeneration may be visible but may not be clearly visible on dark skin. After this stage the bleeding from different areas begins. Bleeding in both the upper and lower digestive tract, the respiratory tract, the urinary tract, the vagina in women can be detected. Continuous petechial in the buccal mucosa, skin and conjunctivae grow. Repeated cleansing bumps that prevent any oral fluid intake and a large amount of wet diarrhea (five liters or more per day) contribute to the loss of excess fluid leading to dehydration. If fluid changes are not enough, bending, extreme fatigue and hypovolemic shock eventually.

Hypovolemic shock was reported in 60% of cases. Despite high body temperature, patients experience cold edges due to peripheral vasoconstriction. Rapid and cord pulses, tachypnea, oliguria or anuria can be detected. At the same time features such as asthma and abdominal pain, muscle and joint pain and headache increase. Although in some cases coughing and dyspnoea occur as a result of pulmonary haemorrhage, other respiratory symptoms are uncommon. Conjunctival injection is a common clinical feature. The most common neurologic symptoms are hypoactive and hyperactive delirium characterized by decreased mental function, confusion, dizziness and unusual tremors. As the disease changes the internal bleeding may also begin but more often by this time the patients are already in a coma.

It is reported that only 5% of patients have bleeding from the gastrointestinal tract before death. Most of the reported deaths occurred as a result of shock during the 7th to 12th day of illness. Symptoms of 40% of patients have improved by day 10 although symptoms such as mouth sores and thrush have already appeared. Most patients who survived until day 13 showed a high chance of finally recovering. Some patients who showed early improvement in symptoms have had stiff necks and reduced cognitive levels associated with late death.

Post-mortem examinations and post-mortem biopsies are very useful in the study of the pathology of the Ebola virus disease. Because of the biosafety risk in autopsy staff when handling models, pathological explanations of only a limited number of available conditions.

The most common findings of Haematoxylin and eosine-stained tissue components are oval-shaped or filamentous eosinophilic intracellular inclusions formed by a combination of viral nucleobases. These implants can be found in macrophages, hepatocytes, endothelial cells, fibroblasts of connective tissue etc. Immunohistochemically stains express viral antigens to various infected tissue cells including macrophages, dendritic cells, epithelial cells and sweat glands, intermediate cells and kidney tubes. , seminiferous tubes, endothelial cells and endocardial cells. In addition necrotic cells and cellular waste contain antigens in abundance. Electron microscopy shows an abundance of free viral particles in the alveolar glands, liver sinusoids, and connective tissue cells of the testis and dermal collagen. Karyorrhexis and apoptosis are found in portal triads cells, macrophages of the red spleen pulp and epithelial cells of the tubular kidneys.

Liver tissue exhibits histopathological symptoms including concentrated or widespread necrosis of hepatocytes and central steatosis. Although inflammation is usually mild, hyperplasia of kupfer cells and infiltration of mononuclear inflammatory cells is observed. The infected lung shows congestion, bleeding and intra-alveolar edoema but inflammation is not significant. Concentrated infiltration of mononuclear inflammatory cells is known to occur in the lamina propria of the small intestine and colon. Skin biopsies reveal dermal edoema, concentrated bleeding, petechiae, ecchymosis, and macular rashes. Spleen and lymph nodes show widespread lymphoid depletion due to apoptosis and necrosis. Inflammation of the kidneys is undetectable although acute tubular necrosis is more common. Even if the heart endocardium contains viral antigens, the myocardium does not show significant damage. Brain histology shows panencephalitis and perivascular infiltration of lymphocytes.

The World Health Organization (WHO) has recommended a set of measures to prevent and control infection in health workers, including safety measures to be taken in the various stages of EVD patient management.

1. General precautionary measures

Regardless of the disease, it is recommended that health professionals take precautionary measures when treating all patients, as it is difficult to diagnose EVD patients at the onset of the disease. These are,

2. Doing hand hygiene

Use disposable gloves before handling items that may be infected w ear eye protection and a coat before engaging in procedures that body fluids may predict.

3. Hand hygiene

Hand hygiene should be done using soap and water or an alcohol-based hand sanitizer solution, in accordance with WHO guidelines, before wearing gloves and protective equipment (PPE) after exposure to a patient’s body fluids after contact with a dirty area or equipment after extracting PPE. if the hands appear dirty.

4. Personal Protective Equipment (PPE)

PPE should be worn before entering EVD patient care facilities in accordance with the WHO-recommended order and removed before leaving the care facility. Contact with used PPE on any part of the face or fragile skin should be avoided. PPE covers,

• Non-sterile gloves are the right size
• Non-slip and long-sleeved dress
• Face shield
• Locked shoes that prevent piercing and intrusion

5. Patient placement and management

Suspected or certified EVD patients should be kept in isolation and if possible kept in a single room. Otherwise they must be placed in beds with a gap of at least 1m in between. Visitors should have no restrictions other than those necessary for the patient’s well-being as a parent.

Management of used equipment and other items

It is recommended that equipment such as stethoscopes be refined and disinfected before reuse, if different equipment is not available. Parental equipment, surgical blades, syringes and needles should not be reused. They should be discarded in barrels that are resistant to piercing. All solid non-solid waste should be disposed of in non-leaky bags or bins.

Used linen should be collected from non-perishable bags stored during use. They should be washed with water and detergent, rinsed, soaked in 0.05% chlorine for 30 minutes and then dried.

All barrels must remain upright and must be closed when ¾ is full. Before being removed from the wards the outer surfaces of these containers should be disinfected using 0.5% chlorine.

1. Clean the environment

Cleaners should wear heavy rubber gloves, and non-slip, non-slip rubber boots over PPE. Water and cleaning should be used to clean work areas and the floor of the hospital. This should be done at least once a day. Some dirty areas and contaminants should be cleaned and disinfected using 0.5% chlorine.

2. Biological management

Performing autopsies, post-mortem biopsies and other laboratory tests of certified EVD tissue samples or suspected patients should be minimized and should only be performed by qualified personnel. Full PPE should be worn during template handling. All specimens should be submitted with clearly marked, non-leaky, non-breakable containers, with an antiseptic exterior.

Carcasses should never be washed or embalmed. They should be sealed in two bags, disinfected with 0.5% chlorine and buried immediately. Some cultural and religious practices can be changed if necessary, but body care should be kept to a minimum and full PPE should be worn at all times.

3. In the case of exposure to infected body fluids

All current operations should be safe and dry immediately and PPE should be safely removed. Affected skin should be washed with soap and water and any affected pores such as conjunctiva should be washed with plenty of running water. The person should be tested for fever and other symptoms for 21 days.

4. Pathogenesis

The pathogenesis of the Ebola virus shows similarity to that of most other filo viruses that include immunosuppression, increased vascular permeability and coagulopathy. The Ebola virus enters the scrotum even through skin scratches, either through mucous membranes or by accidental injection. The virus enters monocytes, macrophages and dendritic cells and is carried by lymphatics to circulation. It then spreads to the liver and spleen to infect tissue macrophages and fibroblastic reticular cell. The main cellular targets of this virus are macrophages, dendritic cells and kupfer cells. The Ebola virus shows an interaction between a variety of cellular proteins which is why the infection is characterized by broad tissue and organ tropism.

5. Immunopathology

In many cases of the virus, the immune system plays a key role in controlling the spread of the virus. However the tissues and organs of the fatal EVD cases show less inflammation, which raises the damage to the immune response.

It has been found that the proteins of the structure of filo viruses e.g. VP24 (Virion protein) and VP35 inhibit interferon reactions and thus avoid the host’s natural defences. As previously mentioned, apoptosis of natural killer cells and T lymphocytes was revealed in histopathology describing the suppression of dynamic immune responses.

As with most complex phones, the Ebola virus infection also causes significant release of pro-inflammatory and vasoactive substances. Even if pro-inflammatory mediators promote inflammation and inflammation, the spread of the infection system is not effectively controlled. This is due to vasodilation connected by active ingredients.

6. Endothelial dysfunction and coagulopathy

The virus attacks endothelial cells and endocardial cells and causes injury (18). This causes internal bleeding, fluid and electrolyte imbalance and cardiovascular failure. Endothelial damage leads to platelet aggregation and use. The increased level of inflammatory factors and increased production of surface tissue factor protein in infected monocytes and macrophages promotes coagulation decay. As a result of hepatocellular damage the production of coagulation factors, fibrinogen, protein C and S also decreases. Other social and economic problems associated with the Ebola virus epidemic

In view of the current outbreak, in addition to the large number of lives that have been claimed by the disease, it has created many other serious problems not only in Ebola-affected countries, but also in other African countries.

Agriculture contributes significantly to the African economy. As more and more farmers die of the disease and many leave their farms for fear of contracting the disease, there is a severe shortage of workers in these countries and a decline in food production. The emergence of food shortages in the near future is predicted by experts.

Chocolate companies and many other industries are particularly affected by the shortage of workers. Nigeria and Ivory Coast are the largest cork producing countries but most of the workers are from Liberia and Guinea. International companies such as Nestle and Mars have introduced education and fundraising programs to prevent the spread of the virus to cork workers.

Many schools have been closed because of a deadly epidemic that has swept across the country. Apart from the impact on education, the child support system in government has stalled as a result.

Tourism is another area affected by the epidemic. Although Africa is a larger continent than Europe, the USA and China combined; visitors often see it as a single country since the Ebola epidemic broke out. For example, Tanzania, a popular wildlife sanctuary, is an East African country, located more than 6,000 miles from the Ebola-affected area. Tanzanian hotels reportedly lost 50% of bookings in 2015.

Many African countries refused to host international events and conferences because of the risk of the Ebola outbreak. For example, Morocco, the host of the Africa Cup of Nations, scheduled for January 2015, is calling for a postponement. The government says, “There is no way we can be serious about the health and safety of Moroccan citizens.”

Download Expository Essay on Ebola Virus

If you want to Download the PDF of the Expository Essay on Ebola Virus you can simply click on the given link it is free of cost.

• Expository Essay on Leadership in 800-850 words | for 6-12 | Free Pdf
• Expository Essay on Science and Technology in 900-1000 words | Free Pdf

1 thought on “Expository Essay on Ebola Virus | 800-1000 words | Free PDF”

Thank you for taking the time to read our blog! We hope that you found it helpful. If so, please leave a comment or rating below, and share this blog with your friends on social media. Thank you again for reading!

Leave a Comment Cancel Reply

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

Notify me of follow-up comments by email.

Notify me of new posts by email.

• Human Editing
• Free AI Essay Writer
• AI Outline Generator
• AI Paragraph Generator
• Paragraph Expander
• Essay Expander
• Literature Review Generator
• Research Paper Generator
• Thesis Generator
• Paraphrasing tool
• AI Rewording Tool
• AI Sentence Rewriter
• AI Rephraser
• AI Paragraph Rewriter
• Summarizing Tool
• AI Content Shortener
• Plagiarism Checker
• AI Detector
• AI Essay Checker
• Citation Generator
• Reference Finder
• Book Citation Generator
• Legal Citation Generator
• Journal Citation Generator
• Reference Citation Generator
• Scientific Citation Generator
• Source Citation Generator
• Website Citation Generator
• URL Citation Generator
• Proofreading Service
• Editing Service
• AI Writing Guides
• AI Detection Guides
• Citation Guides
• Grammar Guides
• Paraphrasing Guides
• Plagiarism Guides
• Summary Writing Guides
• STEM Guides
• Humanities Guides
• Language Learning Guides
• Coding Guides
• Top Lists and Recommendations
• AI Detectors
• AI Writing Services
• Coding Homework Help
• Citation Generators
• Editing Websites
• Essay Writing Websites
• Language Learning Websites
• Math Solvers
• Paraphrasers
• Plagiarism Checkers
• Reference Finders
• Spell Checkers
• Summarizers
• Tutoring Websites

Most Popular

12 days ago

Typely Review

13 days ago

Have You Fallen in the Trap of Compromised AI Learning?

Science.gov review.

11 days ago

Clark County Schools Introduce Cell Phone Pouches to Enhance Learning Focus

23 of 25 students admit chatgpt use after professor’s amnesty offer, symptoms of the ebola virus essay sample, example.

Ebola was first discovered 1976 in Africa, on the banks of the Ebola river, after which the virus has been named. Back then, there were two major outbreaks of the virus, and this is how people learned about it. There exist several strains of the Ebola virus, some of them are deadly to people, and some are not.

The main symptoms of Ebola can appear in a period between the second and the 21st days of contamination, but usually it happens on the eighth through 10th day (CDC). Among the symptoms that appear in the first turn, one should mention fever and chills, strong headaches, pain in joints and muscles, and general weakness. These symptoms are not too different from those that people usually experience when catching a severe cold, or flu, so victims may even ignore these symptoms, or try to treat them as a common sickness. However, as the virus keeps progressing, a patient develops nausea with vomiting, diarrhea, chest and stomach pains, red eyes and rashes over the body, severe weight loss, and bleeding from almost all bodily orifices (Mayo Clinic).

The virus is usually transmitted either through blood or through waste. Contagion through blood usually takes place if a person consumes infested meat, or even touches it (for example, butchering can also lead to contamination). Also, there were cases when people got infected after stepping in feces of infected mammals, mostly bats (Mayo Clinic). The other ways of getting infected is through skin by receiving bodily fluids through pores.

Even though there is no specific cure from Ebola, doctors still try to treat it. In order to diagnose Ebola, doctors usually take tests on such diseases as cholera or malaria, because it is difficult to diagnose Ebola based solely on symptoms. After the diagnosis has been made, doctors start treating the symptoms, which includes eliminating infected cells, electrolytes, blood pressure medication, blood transfusions, oxygen therapy, and so on (WebMD).

Though Ebola is a highly dangerous disease, it is not likely that it will spread globally. It is most deadly in anti-sanitary conditions, which many African countries are notorious for. As for first world countries, even though there is still no universal cure, they are at much lesser risk than African countries. Though the symptoms of Ebola are severe and getting infected is not difficult, with the correct handling of an outbreak, the virus should not be able to spread.

“Signs and Symptoms.” Centers for Disease Control and Prevention. Centers for Disease Control and Prevention, 03 Oct. 2014. Web. 05 Oct. 2014. .

“Ebola Virus and Marburg Virus.” Causes. N.p., n.d. Web. 06 Oct. 2014. .

“Ebola Virus: Symptoms, Treatment, and Prevention.” WebMD. WebMD, n.d. Web. 05 Oct. 2014. .

Follow us on Reddit for more insights and updates.

Comments (0)

Welcome to A*Help comments!

We’re all about debate and discussion at A*Help.

We value the diverse opinions of users, so you may find points of view that you don’t agree with. And that’s cool. However, there are certain things we’re not OK with: attempts to manipulate our data in any way, for example, or the posting of discriminative, offensive, hateful, or disparaging material.

Comments are closed.

More from Expository Essay Examples and Samples

Nov 23 2023

Why Is Of Mice And Men Banned

Nov 07 2023

Pride and Prejudice Themes

May 10 2023

Remote Collaboration and Evidence Based Care Essay Sample, Example

Related writing guides, writing an expository essay.

Remember Me

What is your profession ? Student Teacher Writer Other

Forgotten Password?

Username or Email

Open Access is an initiative that aims to make scientific research freely available to all. To date our community has made over 100 million downloads. It’s based on principles of collaboration, unobstructed discovery, and, most importantly, scientific progression. As PhD students, we found it difficult to access the research we needed, so we decided to create a new Open Access publisher that levels the playing field for scientists across the world. How? By making research easy to access, and puts the academic needs of the researchers before the business interests of publishers.

We are a community of more than 103,000 authors and editors from 3,291 institutions spanning 160 countries, including Nobel Prize winners and some of the world’s most-cited researchers. Publishing on IntechOpen allows authors to earn citations and find new collaborators, meaning more people see your work not only from your own field of study, but from other related fields too.

Brief introduction to this section that descibes Open Access especially from an IntechOpen perspective

Want to get in touch? Contact our London head office or media team here

Our team is growing all the time, so we’re always on the lookout for smart people who want to help us reshape the world of scientific publishing.

Home > Books > Emerging Challenges in Filovirus Infections

Essay on the Elusive Natural History of Ebola Viruses

Submitted: 15 April 2019 Reviewed: 29 July 2019 Published: 01 October 2019

DOI: 10.5772/intechopen.88879

Cite this chapter

There are two ways to cite this chapter:

From the Edited Volume

Emerging Challenges in Filovirus Infections

Edited by Samuel Ikwaras Okware

To purchase hard copies of this book, please contact the representative in India: CBS Publishers & Distributors Pvt. Ltd. www.cbspd.com | [email protected]

Chapter metrics overview

1,248 Chapter Downloads

Impact of this chapter

Total Chapter Downloads on intechopen.com

Total Chapter Views on intechopen.com

This chapter presents a review of what is known about the natural history of the Ebolaviruses in Central and West Africa as well as in the Philippines. All the previous hypotheses on the natural cycle of Ebolavirus are revisited. Also, the main factors driving the virus natural cycle are summarized for the different ecosystems where the Ebolavirus is known to have emerged, including the virus species, the date of emergence, the seasonality, the environmental features, as well as the potential risk and associated factors of emergence. The proposed hypothesis of the Ebolavirus natural cycle prevails an inter-species spillover involving several vertebrate hosts, as well as biotic and abiotic changing environmental factors among other original features of a complex natural cycle. It is also compared with other virus having such type of cycle involving chiropteran as potential reservoir and vector and presenting such original inter-outbreak epidemiological silences. Ultimately, these observations and hypotheses on Ebolavirus natural cycles give some insight into the potential drivers of virus emergence, host co-evolution, and a spatiotemporal dimension of risk leading to identify high risk areas for preventing emerging events and be prepared for an early response.

• natural cycle

Author Information

Jean-paul gonzalez *.

• Division of Biomedical Graduate Research Organization, Department of Microbiology and Immunology, School of Medicine, Georgetown University, USA
• Centaurus Biotech LLC, USA

Marc Souris

• Institute of Research for Development (IRD), France

Massamba Sylla

• Ministry of Health, Senegal

Francisco Veas

• Faculty of Pharmacy, Montpellier University, France

Tom Vincent

• CRDF Global, USA

*Address all correspondence to: [email protected]

1. Introduction

It has been several decades since an unknown fever dramatically emerged, close to the Ebola river, a small tributary of the great Ubangi river in the heart of the Congolese tropical forest of Africa. Since that time, even though the virus responsible for this new hemorrhagic fever has been identified and characterized, the natural history of the eponymic Ebolavirus remains largely unknown. The cradle of the virus remains enigmatic and the emergence of the Ebola fever unsolved. Indeed, the arcane of Ebolavirus natural history is still hypothesized, thanks to an elusive virus that always risen where it was not expected, violent and devastating, and surprising local populations and health systems, as well as the international scientific community. This Ebolavirus eco-epidemiology remains complex while the Ebola fever (alias Ebolavirus Disease) can be considered as an exemplary disease that can be eventually comprehended only with a transdisciplinary approach that has recently been promoted as a One Health concept. Indeed, it is only when we take into account all disease and virus drivers, including biotic and abiotic factors of the natural and human environments, that some mechanisms of the Ebolavirus disease emergence, such as spread and circulation, can be ultimately unveiled. For that, we have collected all information available, often estimated, from the time and place of the virus emergence long before the emerging event was identified as it and the epidemic phase was brought to public attention. Moreover, when available we also collect all data on potential natural and accidental hosts, weather and environment chorology, among other multiple factors potentially involved.

Historically, Ebolavirus emerged in Central Africa in the late 1970s, and has re-emerged most recently with the active epidemic (April 2019) in the eastern Democratic Republic of Congo (DRC), by encompassing more than 24 epidemic events from Central to West Africa, to imported infected monkey from Asia to Virginia, and the emerging new Ebola species of the Philippines archipelago [ 1 ].

Among the negative sense RNA viruses of the Filoviridae family five genera are known, including Cuevavirus, Ebolavirus, Marburgvirus , Thamnovirus . Among the Ebolavirus genus, five Ebolavirus (EBOV) species have been identified [ 2 ].

Ebolavirus’ (EBOV) first emergence occurred in 1976, as two different EBOV species in two different places in sub Saharan Africa. The Zaire Ebolavirus (ZEBOV) species and the Sudan Ebolavirus (SUDV) were detected concomitantly, a few weeks apart, respectively in the Northeastern Equator province of the Democratic Republic of Congo, DRC (alias Zaire), and in the Bahr el Ghazal province of South Sudan. On the 26th of August 1976 ZEBOV was isolated from missionaries and local villagers of the Yambuku, in the rain forest close to the Ebola river. However, earlier in June 1976, the SUDV had broken out among cotton factory workers in Nzara, Sudan (now in South Sudan) [ 3 ].

Then, in 1989, the Reston Ebolavirus species surprisingly (RESTV) emerged in the US (!) and was identified during an outbreak of simian hemorrhagic fever virus in crab-eating macaques from Hazleton Laboratories (now Covance) of Reston county, Virginia. Such primate specimens were found to be recently imported from the Philippines. Then, in 1994 a fourth new species of Ebolavirus was isolated from chimpanzee leaving in the Tai Forest of Côte d’Ivoire and named Côte d’Ivoire ebolavirus (CIEBOV). Finally, in November 2007, a fifth Ebolavirus species, was detected from infected patients in Uganda in the Bundibugyo District and was subsequently identified by the eponymic name of Bundibugyo Ebolavirus [ 4 ].

Briefly and extraordinarily among the world of the viruses, the filovirus virion presents a bacilliform (filamentous) shape, like a Rhabdovirus, but presents unique pleomorphic figures with branches and other tortuous shapes. Ebolaviruses have also an unusual and variable long length - up to 805 nanometers (only some plant virus can compete to this filamentous extensive length). However, the internal structure is more classical with a ribonucleoprotein nucleocapsid, a lipid envelope and seven nanometers size spikes. The genome is non-segmented, single stranded RNA of negative polarity with lengths of about 18.9 kb that code for seven proteins, each one having a specific function [ 5 ].

Ebolaviruses are known for their high case-fatality rate (CFR) with always less than 2/3 of survivors among the identified cases. ZEBOV, the most frequently isolated Ebolavirus species during the outbreaks, has the highest CFR, up to 90% in some instances, with an average of 83% for the past 37 years. The Uganda BDBV outbreak had a mortality rate of 34%. RESTV imported to the US did not cause disease in exposed human laboratory workers. The scientist performing the necropsies on CIEBOV infected chimpanzees got infected and developed a Dengue-like fever, fully recovered 6 weeks after the infection while treated in Switzerland.

2. When Ebolavirus raised his head in the heart of darkness

Dates and time make History. Indeed, the various reports on the emergence of Ebolavirus in Africa show discrepancies and lack accuracy, for multiple reasons (remote event, reports by different person or team, at different time…) but the only way to forge the history is to label the events with date, time and the environmental factors observed. On July 27, 1976, the first (known) victim to contract Ebolavirus was a cotton factory worker from Nzara, Sudan. Then, in Zaire (DRC) on September 1, 1976, the first Ebolavirus (Zaire ebolavirus, ZEBOV) victim was a teacher who had just returned from a family visit to northern Zaire (6 Jennifer Rosenberg Internet). These two events were the very beginning of the boundless journey of a deadly Ebolavirus outbreaks.

2.1 The Ebolavirus species emerging events

When the virus becomes epidemic in a human population, it does so weeks or months after the emergent event of the virus switching from its silent transmission in a natural cycle to a zoonotic/epidemic manifestation, revealed to the local health system. Let us see in more detail such emerging events of Ebolavirus species (ICTV, 2018) as there were reported or sometime interpreted, in time and place.

Sudan ebolavirus (SEBOV) occurred when the first recorded SUDV broke out among cotton factory workers in Nzara, South Sudan in June 271,976. This was indeed, the first case of Ebolavirus infection recorded and confirmed and also reported as potentially exposed to chiropteran. Indeed, at the Nzara Cotton Manufacturing Factory this first patient was a cloth room worker where bats (mostly Tadarida - mops - trevori ) have a large population in the roof space of their premises. He died in the Nzara hospital on July 6, 1976. Local animals and insects were tested for Ebolavirus without success [ 6 , 7 ].

Zaire ebolavirus (ZEBOV) was reported in the Mongala district of the Democratic Republic of Congo (DRC; alias Zaire) in August 1976, when a 44-year-old schoolteacher of the Yambuku village, became the first recorded case of Ebolavirus infection in DRC. Also, the schoolteacher travel earlier in August 1976 near the Central African Republic border and along the Ebola River, estimated 90 km NW from the village [ 6 ].

Reston ebolavirus (REBOV) had its first emerging event as an imported infected cynomolgus monkey ( Macaca fascicularis ) in October 1989 imported from a facility in the Philippines (Mindanao Island) to Reston, Virginia, USA, where the primate got sick and the virus isolated [ 8 ]. In the Philippines, in several instances, the virus was found to infect pigs, in June and September 2008 ill pigs were confirmed to be infested by REBOV (Ecija and Bulacan, Manila island), as well during 2008–2009 epizootics in the island of Luzon (Philippines) [ 9 ].

Cote d’Ivoire ebolavirus (CIEBOV) was isolated for the first time, and as an only known appearance, in November 1994, from wild chimpanzees presenting severe internal bleeding of the Taï Forest in Côte d’Ivoire, Africa. A researcher became infected when practicing a necropsy on one of these primates, he developed a dengue syndrome and survived. At that time, many dead chimpanzees were discovered and tested positive for Ebolavirus. However, the source of the virus was believed to be of infected western red colobus monkeys ( Piliocolobus badius ) upon which the chimpanzees preyed [ 10 ].

Bundibugyo ebolavirus (BDBV) was then discovered during an outbreak of Ebolavirus in the Bundibugyo District (Bundibugyo and Kikyo townships), on August 1st, 2007, in Western Uganda (Towner et al. [ 11 ]). BDBV second emerging event was observed in the DRC in August 17, 2012 in Isiro, Pawa and Dungu, districts of the Province Orientale [ 11 ].

With the exception of REBOV in Philippines and CIEBOV in West Africa, all other EBOVs species emerged in the Central African region. Also, all EBOVs are known to emerged in the tropical rain forest during the inter-season between dry and rainy seasons. Also, REBOV appears to actively circulate in the tropical rain or moist deciduous forest of the Philippines [ 12 ].

2.2 From Central Africa to West Africa

2.2.1 concurrent emergences of ebolaviruses.

On several occasions, concurrent emerging events of Ebolavirus have been observed. Indeed, such events occurred in places geographically distant, independent, and unconnected. The Ebolavirus was isolated and the strains different, even they belonged to the same species of Ebolavirus, altogether in favor of a different origin from an elusive natural reservoir, thus eliminating the notion of leaping from one site to the other. In that matter, the following observations are a paradigm: From its inceptive emergence the Ebolavirus was identified in Sudan at the cotton factory and a few days later at Yambuku, Zaire. The Ebola Sudan and Ebola Zaire viruses emerged concurrently in 1976 in the Congo basin of Central Africa; More than 20 years later the virus emerged and reemergence from 1994 to 1996 in a different places in Gabon, in a successive and timely overlapping events but in unconnected areas from where different strains of the same EBOVZ were isolated [ 13 ]; More recently, during the 2014–2016 dramatic Ebolavirus disease (EVD) emergence of in West Africa where the virus emerged in late December 2013 of a 18-month-old boy from the small village of Meliandou (Guéckédou district, South-Eastern Guinea) believed to have been infected by bats [ 14 ], concurrently, in August 2013, the Ebolavirus reemerged in the Equator province of DRC - different places and different strain of ZEBOV [ 15 ].

It is remarkable that most of these emerging events occurred during or close to the end of the rainy season which generally stretches from August to October in the domain of the Congo basin tropical rain forest.

Altogether, these observations are in favor of environmental factors of emergence favoring, when they occur synchronously in the same place, the spillover of the virus from its hidden natural cycle to an accidental and susceptible host. Therefore, these plural and concomitant emerging events play against the theory of Ebola virus diffusing in oil spot in Central Africa [ 16 ]. This original pattern of concurrent emergences could explain also the relative stability of the virus strains which remain for years in the same environment, and the interepidemic silences which require several fundamentals (i.e. concurrent risk factors) to be broken.

2.2.2 An unexpected broader domain of Ebolavirus circulation

The first evidence that showed that Ebola virus had previously circulated in areas without any known cases of disease came in 1977, near the Ebola outbreak in Tandala, DRC, just 200 miles west of the first known cases in 1976 [ 17 ]. Blood samples obtained from individuals in areas with no previous symptoms of Ebola were found to contain antibodies for Ebolavirus, indicating a previous or ongoing infection with that virus. Because subclinical illness is always a possibility with viral infections, the presence of these Ebolavirus-specific antibodies could only be explained by exposure to the virus, which is somewhat reasonable in an area that is endemic to the disease. But how do we know the true endemic zone of a virus such as Ebolavirus?

Endemic zones are primarily based on where disease can most likely be expected, and are determined by historical accounts of disease, as well as supplemental information such as where animals or insects that might transmit the disease are located. With respect to the Ebola virus, outbreaks that occur in Central Africa, in or near the Congo River Basin, are expected; outbreaks that take place elsewhere are unexpected and can be problematic, as was the case for the 2014–2016 West African outbreak. And yet, scientists have highlighted the presence of Ebola antibodies well outside the endemic zone for disease for decades.

In the early 1980’s, research based at the Pasteur Institute in Bangui, Central African Republic, demonstrated for the first time that the population of central Africa presented natural antibodies against the Ebolavirus strains of Zaire and Sudan [ 3 , 4 ]. Research also showed for the first time that several mammal species had Ebolavirus-reacting antibodies, including rodents, dogs, and others. Initially, the scientific community was skeptical of the findings, due to the type of antibody tests used, and because the prevalence of these antibodies was unbelievably dispersed and at a high level of prevalence. However, a 1989 follow-up study confirmed methodology and preliminary observations, and expanded the results to include similar observations in Cameroon, Chad, Gabon, and Republic of Congo (the latter two of these countries would have their first Ebola outbreaks in 1994 and 2001, respectively) [ 5 ]. Moreover, such Ebolavirus antibody prevalence was found in West Africa (e.g. Senegal, Chad, Sierra Leone), preceding the catastrophic 2014–2016 Ebolavirus outbreak [ 18 ]. Subsequent studies have determined that 20–25% of persons living in or near the Congolese rain forest are seropositive for Ebola, despite never exhibiting symptoms [ 19 ].

Today, Ebola antibody prevalence is widely distributed across the African continent in the absence of severe clinical presentation and/or outbreak manifestation. A 1989 study even found Ebola Zaire antibodies among people living in Madagascar, an island country that has never had a single known case of Ebola, and which has been geographically separated from continental Africa for 100 million years [ 20 ].

Risk mapping, including ecological and geographical distribution <10-13 cm/s first hour, and extended, highly sensitive and specific environmental and biogeographical models based on EBOVs susceptible mammalian biogeography in Africa, show a robust and precise potential distribution of EBOVs in Africa that clearly overlap the African tropical rain forest biome of the Guinea-Congo forests (including the Congo basin rain forest, and the Occidental relic of the Congolese rain forest spreading from Guinea to Ghana) and the southern band of the Sudan-Guinea Savanna [ 21 ].

Also, as a result of potential Ebolavirus (or Ebolavirus antigen) exposure, serological markers have been found in vertebrates outside of Africa. With the exception of Philippines, where REBOV is known to circulate in monkeys and pigs, thus showing its ability to infect multiple animal species, in several instances serological evidence of Ebolavirus exposure has been detected in many vertebrates, particularly chiropterans [ 9 ]. Definitely, bat populations in Bangladesh and China present antibodies against ZEBOV and REBOV proteins [ 22 , 23 ]. Ultimately, it appears that EBOVs are widely distributed throughout Africa, West and Central, and Asia. Moreover, risk mapping of filovirus ecologic niches suggests potential areas of EBOVs distribution in Southeast Asia [ 24 ].

The unexpected detection of REBOV first in Virginia, for the reason we know, and then the astonishing discovery of its circulation and natural cycle in the Philippines gave a rethinking of the entire family of Ebola viruses previously known mainly on the African continent [ 25 ].

From these observation and facts, the potential circulation of EBOVs in its natural cycle appears much wider than expected, while the emerging events we can witness appears to be only a tip of the iceberg in the wide Congolese tropical rain forest.

2.3 From the index case to the epidemic chain, outbreak, and pandemic

The fundamentals of emergence are changing in the heart of the rainforest and elsewhere: changing times, when the means of transmission switch from foot to motorbike, when knowledge conveyance has switched from paper reporting to the internet.

Let us examine the risk of expansion for Ebolavirus. Indeed, the factors of transmission of the virus to man and man to man are essential to take into account in this context. Moreover, it is extremely important to note that these factors are subject to permanent changes in societies whose trade and means of communication are drastically changing as a result of health systems, responses and preparedness for epidemics at national and international levels, policies, and the economy.

So, with the experience gained for more than 40 years, the strategies of struggle are clearly defined, but the societal changes that are taking place make their application difficult and sometimes impossible (e.g., the 2019 outbreak in the DRC, where political institutions have prevented an adapted response). Situation and the epidemic are perpetuated.

There is also a growing means of communication, both smartphones and motorized transport, to travel more quickly as ever, between the epidemic zone of EVD and the family [ 26 ].

Thus, during the emergence of the Ebola virus in West Africa, all of this means of communication played a fundamental role in the regional spread of the epidemic, until it became a pandemic risk when the virus was exported to other countries of the African continent and, outside Africa in Europe and North America [ 27 ].

3. A strange iteration of epidemic events with unexplained virus disappearance

It is known for several other transmitted viruses that during the inter-epidemic silences several factors can be responsible. In general mass herd immunity (natural of due to acquired immunization i.e. vaccine) of the permissive hosts force the virus in its natural cycle without apparent clinical manifestation in the hosts (e.g. Most by the arbovirus classically yellow fever, Dengue, Japanese encephalitis, West Nile, Zika etc.).

The Paramyxoviridae and Rhabdoviridae are the two other viral families in the order Mononegavirales, genetically closely related to the Filoviridae and having chiropteran as reservoir and/or vector [ 28 ]. Indeed, it is interesting to note that megachiropteran fruit bats are reservoirs of Hendra and Nipah viruses of the Paramyxoviridae family [ 29 ]. When, Microchiroptera bats are the probable ancestors of all rabies virus variants of the Lyssavirus genus in the family Rhabdoviridae and infecting presently terrestrial mammals [ 30 ]. Both also present this cryptic interepidemic silences that has not been yet clearly understood. The Nipah emerged one time in Malaysia (1999), thought to have its original cycle in PNG, and ultimately reemerged more than 3500 km away in Bangladesh in 2001. From its inception, again the Marburgvirus (the closest to EBOVs in the family of Filovirus), emerging events from an expected natural foci occurred within the path of time including 4 to 11 years of inter-epidemic silences occurring mostly in distant sites of Eastern and South Africa (Uganda, Zimbabwe, Angola, Kenya).

If one were to describe the history of Ebola outbreaks, one could simply construct a timeline, with a point on the line for each outbreak. You could create this timeline with a varying number of points, depending on your methodology, but regardless of how you built your timeline, there would be spaces between these points. This is due to the nature of Ebola; it appears, it disappears, and it appears again. To the Ebola virus, these gaps are periods of convalescence. To us, they are periods of absence and mystery, and one of these gaps stands out as the most mysterious ( Figure 1 ).

Timeline of Ebolavirus emergence. Emerging events (bars) red = EBOV; blue = SEBOV; green = BDBV; horizontal axis = years 1972–2018; vertical axis = no value. Numbers above brackets = years of silent inter-emerging event.

The CDC lists five Ebola outbreaks in the late 1970’s. The “first” Ebola outbreak took place in 1976, though we now recognize the event as two simultaneous and separate outbreaks. Between June and November 1976, 284 cases (151 deaths) of Ebola Sudan occurred near what is now Nzara, South Sudan; between September and October 1976, 318 cases (280 deaths) of Ebola Zaire occurred near what is now Yambuku, Democratic Republic of Congo (DRC). In November 1976, a researcher in England that was working with samples from the Nzara outbreak accidentally infected himself; CDC lists this accident as the third Ebola outbreak (the individual recovered). In June 1977, a child became sick and died from Ebola Zaire in Tandala, DRC though there was only one confirmed case, subsequent epidemiological investigations of the area uncovered several other historical, probable cases. Finally, between July and October 1979, 34 cases (22 deaths) of Ebola Sudan occurred, unbelievably, in Nzara, Sudan – the same community where the first cases of Ebola emerged just 3 years prior. In the span of just 39 months, the terror of Ebola had introduced itself to the world five times (638 cases, 454 deaths) and then… silence.

Ebola would not reappear for 10 whole years, and even then, the subtype was Ebola Reston, which we now know does not affect humans. Though CDC lists four Ebola Reston outbreaks between 1989 and 1992, the world would not see another case of Ebola virus disease in humans until late-1994, in Gabon. Even then, the outbreak (52 cases, 31 deaths) was mischaracterized as yellow fever for several months. Perhaps the virus’s long absence from the spotlight had removed it from the collective consciousness in 1994, certainly in the presence of those pathogens that had been circulating and consuming our attention in the meantime.

This fifteen-year disappearance of Ebola, particularly in light of its frequent and severe outbreaks in the late 1970’s, has perplexed researchers for decades. The mystery lay, to some extent, within the lack of complete knowledge of the virus reservoir, though scientists are now having their long-held suspicions in bats confirmed. It’s hard to detect disease when you cannot pinpoint the source. Surveillance and reporting have been another confounding element. How many times in that fifteen-year period was an illness misdiagnosed as yellow fever, dengue hemorrhagic fever, or some other similar illness, because of lack of knowledge or diagnostic capabilities, or simply because there was no health care around? We will probably never be able to answer this question. Finally, our perceived zone of endemicity at the time was limited to northern DRC and southern Sudan. Was the virus appearing elsewhere, unbeknownst to us? We certainly were not expecting it to emerge in Gabon in 1994, and Uganda in 2000, and West Africa in 2014 [ 31 ].

Scientists today continue to be perplexed by the emergence of the virus. What brings Ebola out from its hiding place? Is its emergence/re-emergence tied to climate change? globalization? the changing interface between humans and wildlife? If it has to do with any of these increasingly significant factors, how do they explain the fifteen-year disappearance?

These days, the virus comes and goes with some predictability—since 2000, outbreaks have approached a near-annual incidence, sometimes skipping a year, sometimes lasting more than a year. The periods between outbreaks are growing shorter. Is this because our capability to detect Ebola outbreaks is improving, or is the virus able to infect humans more frequently? One thing is for sure: the world knows that when one outbreak ends, another will eventually follow, and we need not wait 15 years.

4. Toward the discovery of the natural cycle of the Ebolaviruses

4.1 the discovery of a putative natural reservoir of ebolavirus.

Since the ZEBOV and SEBOV emergence, extended field studies have been conducted to discover the reservoir of EBOVs [ 32 ] including the 1976 first recorded DRC outbreaks and Sudan, the 1979 outbreak in DRC in 1979 and 1995 following the Kikwit outbreak, the same year in the Tai Forest and in 1999 in the Central African Republic [ 33 , 34 , 35 , 36 , 37 , 38 ] . A total of more than 7000 vertebrates and 30,000 invertebrates were sampled and tested for the presence of EBOVs. Limited finding was inconclusive for an potential EBOVs reservoir status among all these animals. Moreover, while several animal species (Bats, birds, reptiles, mollusks, arthropods, and plants) were experimentally infected with ZEBOV, only two fruit bat species ( Epomophorus spp. and Tadarida spp.) developed a subclinical transient viremia [ 39 ]. If these results were not confirmed in the natural settings, they indicated the potential for chiropteran to be natural for EBOVs [ 40 ].

Also, historically, the first documented case of EVD in Sudan in 1976, the index case was located (by the World Health Organization) in a cotton factory far from the forest block, where the only wild significantly abundant species was an insectivorous bat species [ 21 ].

Since the discovery of EBOV in 1976, more than half of the epidemic outbreaks caused by EBOVs have broken down between Gabon and the DRC. Following the successive EBOV outbreaks in Gabon from 1995 to 2001 affecting several animal species non-human primates, and wild ungulates and responsible of the dramatic decline of great apes (gorilla and chimpanzee) populations in the region (Leroy et al. [ 16 ]), researchers engaged several missions of captures of wild animals in the forest areas affected by the recent past epidemics. Also, 1030 animals were captured and analyzed, only three species of fruit bats were found infected with the ZEBOV by PCR including: Hypsignathus monstrosus ; Epomops franqueti; and Myonycteris torquata . Moreover, antibody reacting anti-Ebola were detected in these species as well as for the genus Myonycteris spp. leading ultimately to design Chiropteran as a potential reservoir of EBOVs [ 41 ].

Since then, many studies have converged in favor of the role of chiropters in maintaining EBOV in the wild (Caron et al. [ 42 ], Leendertz). In addition, a recent study of bats in Sierra Leone showed the association of an EBOV like with several species of bats ( Mops condylurus and Chaerephon pumilus ) from the Molossus family [ 43 ]. Moreover, a potential direct exposure to Ebola infected fruit bats was also reported as a putative index case of large epidemics [ 44 , 45 ]. Moreover, further studies reported on direct infection of natural hosts (primates) by EBOV infected bats as highly plausible, given that bats, especially fruit bats, are frequently hunted and consumed as bushmeat by human when Cercopithecus species hunt roosting bats for consumption [ 46 ] also preying on bats has been reported in Cercopithecus ascanius and C. mitis (East Africa) as well as bonobos (DRC) [ 47 ]. It is also possible that different modes of exposure to Ebola virus could lead to different antibody profiles, that is, contaminated fruit vs. contact with infected bats during hunting [ 44 , 47 , 48 ].

Altogether, several fruit bats ( Epomophorus wahlbergi ) and insectivorous bats ( Chaerephon pumilus, Mops condylurus ) experimentally survive to EBOV infections [ 39 ], EBOV RNA and/or anti EBOV reacting antibodies were detected also in several other fruit bat species ( Epomops franqueti, Hypsignathus monstrosus, Myonycteris torquata , Eidolon helvum, Epomophorus gambianus, Micropteropus pusillus, Mops condylurus, Rousettus aegyptiacus, Rousettus leschenaultia ) giving more insight of the potential for chiropteran to be a potential host or reservoir host of EBOVs [ 22 , 49 , 50 ].

Interestingly, REBOV was also found associated with the bats in its natural habitat of the Philippines [ 51 ]. Also, again in this same Filoviridae family, Marburg viruses in Africa are clearly associated with bats [ 32 , 52 ] as well as the Cueva virus in Europe [ 53 ]. While REBOV has been find associated with fruit bats, Roussetus spp. (Pteropodid family), each filovirus genus is associated with a specific chiropteran group including: Marburgvirus with a specific fruit bat, Roussetus aegyptiacus (Pteropodid family); and Cuevavirus with insectivorous bat, Miniopterus schreibersii (Miniopterid family); except for Thamnovirus isolated form fresh water fish.

Moreover, several virus groups are known to hold bat-borne viruses including the coronaviruses, hantaviruses, lyssaviruses, lassa virus, Henipavirus, filovirus which are among the most severe of the emerging viruses [ 54 , 55 ].

Conclusively, this was the first evidence of chiropteran as a potential reservoir and/or vector of EBOV, while several wild animals, in particular great apes were find highly sensitive to EBOV infection. Also, if several species of chiropteran have been identified as a potential virus reservoir,

4.2 The most complete figure of a putative Ebolavirus natural cycle in the central African raining forest

From all above observations, records and historical events of EBOVs emerging events, several fundamentals of emergence have been identified as well putative time and space of such events where, that is when the virus jump from the cryptic natural cycle of the reservoir-vector to manifest itself clearly as an open index case of infection in a susceptible host and the potential opening epizootic or epidemic chain.

4.2.1 The actors

Again, from the literature numerous vertebrates appears to be permissive to infection by EBOVs, however, due to their ethology, including environmental habits, societal structure, density and their ability of intra and interspecies to mingle. Altogether primates appear highly susceptible to EBOVs infection including non-human primate apes, gorilla and chimpanzee, but also cercopithecids (e.g. colobus) but also small wild ungulates (e.g. forest duikers) and eventually domestic animals (e.g. dogs) [ 32 , 56 , 57 , 58 ].

One can summarize that EBOVs natural hosts belongs to chiropteran as a potential host reservoir represented mostly by Pteropodidae in Africa (REBOV and Roussetus; Bombali virus and Molossidae), and as secondary natural or accidental wild and domestic hosts including several other mammals: primates (Colobus, Cercopithecus), non-human primates (Gorilla, chimpanzee), wild ungulates (duikers) and, human primates. Also this needs to be taken into account with respect to other permissive species to EBOVs, indeed, as an example, if Roussetus spp. was shown to carry EBOVs reacting antibodies more recently R. aegyptiacus bats were demonstrated to unlikely able to maintain and perpetuate EBOV in nature while the natural transmission of filovirus in R. aegyptiacus , resulting viral replication and shedding are unknown [ 59 ].

4.2.2 The stages

The African Rain forest of the Congolese basin appears to be the epicenter of EBOVs emerging events. More than 80% of the emerging events of EBOVs occurred in the Tropical zone under the influence of the (Intertropical converging zone, ITCZ) from five degree North to 5 degrees south and oscillating as much as 40 to 45° of latitude north or south of the equator based on the pattern of land and ocean beneath it [ 28 ] ( Figure 2 ).

Emerging events of Ebolavirus and climate since the Ebola fever inception in Africa. Left = annual rainfall; right = annual temperature. To illustrate the association temperature/rainfall and emergence, the month of May was chosen because it is at this time of the year that we observe the most emergent events of the Ebola virus. Temperature and rainfall are expressed as an annual average for the period under consideration. The precise location of 32 Ebola emergent events are here integrated into the global climatic map of Africa. Only 30-year average values per month of rainfall are available for the study period (ref.: WorldClim world databases) as well for the average monthly temperature.

Temperature and precipitation data for Africa (average data computed from 1960 to 1990, 300 m resolution [HIJ 05]) were integrated with the distribution map of the emergent events of the Ebola virus and the values ​​calculated for each of the emergence points [ 60 ].

On all emergence points, the temperature at the time of emergence is not significantly different from the average annual temperature over 30 years. The difference in temperature between the moment of emergence and the average temperature (of 30 years monthly average) of the hottest month does not show any difference either. Emergence would not be directly related to temperature.

When we compare Ebolavirus emerging events time and the rainfall, there is strict quantitative correlation between rainfall and emergence: Most of the emergent events (93.8%) occurred during the rainy season ( Figure 2 ). For precipitation values, there is a slightly statistically significant (p = 0.02) positive difference between the average precipitation of the month of emergence and the average of the monthly average precipitation (over 30 years), indicating that precipitations are higher when emergences occur. There is an even more statistically significant (p = 0.003) positive difference when considering precipitation of the month preceding the emergence. Emergence is therefore likely to be associated with rainfall intensity and the rainy season. 10/32 emergences occur at the beginning of the rainy season, 9/32 in the middle, and 11/32 at the end. Only 2/32 emergences occurred in the dry season.

When referring to land use ( Figure 3 ) the temperature at the 6 emergence points in “Cropland” is highly significantly less (p = 0.005) than 15% (21.6°C) at temperature (24.4°C) to the 9 points in “Tree cover, broadleaved, evergreen, closed to open”, however the average temperature of the Cropland (21.6°) is to a degree less, significantly lower (p = 0.01) than that of the “Tree cover” (24.5°C).

Environmental factors surrounding Ebolavirus emerging event: Land use and places of Ebola virus emergence in Africa from 1976 to 2014. Land use from ESA 2015, 300 m resolution; red circle = putative place of the Ebola virus emergence (index case). Estimated Ebola emergence places are superimposed on the land use layer. The identification of the land use types were 32 points (red circle) representing the putative places of Ebolavirus emergence are superimposed and are distributed as follows: (1) cropland: 6, (2) herbaceous cover: 5, (3) cropland mosaic: 5 (> 50% natural vegetation vs. <50% tree, shrub, herbaceous cover), (4) tree cover with: (a) 15% of broadleaved, evergreen, closed to open: 9, (b) 15–40% of broadleaved, deciduous, open: 2, (5) flooded, fresh or brackish water: 1, (6) urban areas: 3, and (7) water bodies: 1. The limitations of this interpretation are linked to the accuracy of the location of Ebolavirus emergence sites (from literature and reports) and, to the evolution of vegetation cover over the past decades since the first emergence of the Ebolavirus occurred in Africa.

Ultimately, taking into account these environmental factors, when we look for an association between the emergent events of the Ebola virus and the characteristics of the places of these emergences (i.e. land use, temperature, rainfall) it turns out that the emergences are always in the zone of heavy rainfall, but nevertheless do not follow the moving of the rainy season. Moreover, these emergences remain always and remarkably close enough to the Equator, therefore in the equatorial forest area with a high hygrometry, and a moderate annual temperature. However, the temperature at the time of emergence is not significantly different from the average annual temperature (at the points of emergence) which does not allow to distinguish seasonal effect in the emergence-temperature relationship. Conclusively, we did not identify a seasonality associated with the time of emergence, however the emerging events occur in specific geographic zone characterized by several environmental factors. Finally, the emergence zones are in areas of Land Use with specific temperatures not related to seasonality. Ultimately, it is also remarkable that all these emerging events occurred in an area with a highly potential presence of apes, virus-sensitive hosts.

4.2.3 Fundamentals and domains of emergence: a theory for a natural cycle of EBOVs in Africa

Also, the EBOVs species are closely genetically related, their seems to occur by foci in nature. The host appears to be the same, natural or accidental, and the transmission done by direct contact with infected hosts or its biological products [ 50 , 61 ]. Altogether, in the early 2000s, before the identification of chiropteran as a potential host-reservoir of the EBOVs, a hypothetic natural cycle was described empirically based on seasonal environmental climatic factors [ 55 ]. Then, taking into account bats as a potential reservoir-host, the question of virus transmission was central to consider while environmental factors appears to play a major role to the host and their natural cycle (Chiropteran physiology) (climate/fructification, chorology, bats physiology). Several factors of emergence were then listed including: Chronic infection, infected organs, virus shedding, close encounters between reservoir and susceptible hosts, food and water resource, seasonality, chorology (i.e. causal effect between geographical phenomena – season) in the tropical rain forest and the spatial distribution of chiropteran (i.e. index site of Ebola emerging events).

Epidemiological field surveys indicate that mass mortalities of apes and monkey species due to Ebola virus often appear at the end of the dry season, a period when food resources are scarce. Restricted access to a limited number of fruit-bearing trees can lead to spatiotemporal clustering of diverse species of frugivorous animals, such as bats, nonhuman primates, and other terrestrial species foraging on fallen partially eaten (by bats) fruits. These aggregates of wild animal species favor the contact between infected and susceptible individuals and promote virus transmission. The dry season aggregation of reservoir host species involved in natural maintenance cycles, augmented by incidentally infected secondary hosts serving as sources for intra- and interspecific transmission chains independent of repeated spillover from the reservoir host, provides an ecological setting for amplifying enzootic transmission of Ebola virus when a vertebrate hosts are concentrated around a scarce number of water sources [ 62 ].

In addition to this dietary impoverishment, there are behavioral and physiological events occurring among bats during the tropical dry favor the contact frequency and intimacy between bats, which can promote transmission of Ebola virus to others and increase R0. As an example, megachiropteran fruit bats breeding activities and intraspecific competitions between males and grouped kidding of females favor the contact between individuals. Moreover, pregnancy can involve physiological changes among female bats that alter immune functions and eventually favor virus shedding. Parturition among the African megachiropteran bats occurs throughout the year, although seasonal peaks provide birthing fluids, blood, and placental tissues, potentially Ebolavirus infected, falling on the ground as a medium highly attractive and readily available to scavenging terrestrial mammals [ 50 , 56 , 63 ] ( Figure 4A and B ).

(A) Understanding Ebolavirus enzootic and epidemics. Red arrows = cycles of transmission; dashed square = a putative natural cycle of Ebolavirus in Central Africa (see B). Fruit bats are considered to be a putative reservoir of Ebola virus in Central Africa after 2004; In 2009, several non-human primate epizootic are reported; 1976 was the first emerging events and subsequent epidemic chains in remote area of the rain forest and close by; 2012 showed a dramatic spread of the virus associated with motorized transportation and ground network; In 2014 urban epidemics are reported as well as a pandemic risk and become an international public health emergency. (B) Putative natural cycle of Ebolavirus in Central Africa. Red arrow indicates Ebolavirus transmission. Numbered red circle of transmission: (1) sylvatic inter- and intra-species transmission; (2) chiropteran migration; (3) chiropter to primate (close contact of dejection); (4) primate inter species (Cercopithecus/chimpanzee); (5) primate to primate (non-human primates); (6) non-human primate epizootic (gorillas); (7) chiropter to duikers; and (8) consumption of chiropteran infected food by shrew or wild pig.

5. If we had to conclude

Based on historical data and observations, the presented hypothesis of the natural cycle of Ebolavirus emergence prevail an inter-species spillover as the complex natural cycle involving several hosts (reservoir, vector, amplifier), as well as biotic and abiotic factors in a changing environment among other original features.

Although the natural cycle of EBOVs remains in the darkness of the rain forest, strong findings and comparative analysis of close parents of the filovirus throw some light to a potential natural cycle of EBOVs in Africa. EBOVs clearly appear linked to chiropteran and dependent for merging events in the environmental factors. Indeed, it appears that filoviridae are often associated with chiropteran while the emergence of the virus strains occurs as a sparse focus with a silent period of cryptic virus circulation. When virus transmission, i.e. spillover, from a hidden natural cycle, to accidental hosts occurs, it happened in a specific time-frame often linked to the season.

One can retain is that the EBOVs complex natural cycle is yet not on entirely elucidated and certainly dependent on environmental factors – associated with a specific environment of the chiropteran species incriminated (i.e. Different territories, different cycle) - leading to multiple, sometime concurrent, temporally and timely emergence in focus.

Although, other hypothesis has been suggested elsewhere including the Ebola virus Disease as an arthropod borne disease among others [ 42 ], there is important fundamental matters to consider as well before providing more.

However, beyond these hypotheses, fundamental questions subsist in order to go further learn. We can cite in particular the mystery of kin between the Reston virus of Asia and the Ebola viruses of Africa, would there not be a missing link in a geographic area yet to discover. Do the filovirus exist in the Americas hidden in the darkness of the tropical forest? Also, the Ebolavirus seems genetically stable, related to particular species of chiropter, was it to think about a co-evolution of the host and the virus in this closed environment of the forest of the tropical? Today, with the endless epidemic unfolding in the DRC, should we revisit our tools and strategy of struggle in an ever-changing world? [ 64 ].

Acknowledgments

We sincerely thank for their supports, brings to all the authors of this deep and never-ending research and scientific thought around an outstanding and fascinating subject: Georgetown University, Centaurus Biotech LLC., The DHS Emeritus Center for Emerging Zoonotic and Animal Diseases at Kansas State University.

Conflict of interest

All authors do not have any conflict of interest whatsoever with this published manuscript.

• 1. CDC. Page last reviewed. Content source: Centers for Disease Control and Prevention, National Center for Emerging and Zoonotic Infectious Diseases (NCEZID), Division of High-Consequence Pathogens and Pathology (DHCPP), Viral Special Pathogens Branch (VSPB). 2019. Available from: https://www.cdc.gov/vhf/ebola/history/2014-2016-outbreak/index.html
• 2. ICTV. Filoviridae. 2019. Available from: https://talk.ictvonline.org/ictv-reports/ictv_online_report/negative-sense-rna-viruses/mononegavirales/w/filoviridae
• 3. Kuhn JH, Andersen KG, Baize S, Bào Y, Bavari S, Berthet N, et al. Nomenclature- and database-compatible names for the two Ebola virus variants that emerged in Guinea and the Democratic Republic of the Congo in 2014. Viruses. 2014; 6 (11):4760-4799. DOI: 10.3390/v6114760
• 4. MacNeil A, Farnon EC, Morgan OW, et al. Filovirus outbreak detection and surveillance: Lessons from Bundibugyo. The Journal of Infectious Diseases. 2011; 204 :S761-S767
• 5. Kiley MP, Bowen ET, Eddy GA, Isaäcson M, Johnson KM, McCormick JB, et al. Filoviridae: A taxonomic home for Marburg and Ebola viruses? Intervirology. 1982; 18 (1-2):24-32
• 6. Anonymous. WHO/INTERNATIONAL STUDY TEAM. Ebola haemorrhagic fever in Zaire, 1976. Bulletin of the World Health Organization. 1978; 56 (2):271-293
• 7. Anonymous. WHO/INTERNATIONAL STUDY TEAM. Ebola haemorrhagic fever in Sudan, 1976. Bulletin of the World Health Organization. 1978; 56 (2):247-270
• 8. Centers for Disease Control. Ebola-Reston virus infection among quarantined nonhuman primates–Texas, 1996. Morbidity and Mortality Weekly Report. 1996; 45 :314-316
• 9. Miranda MEG, Lee N, Miranda J. Reston ebolavirus in humans and animals in the Philippines: A review. The Journal of Infectious Diseases. 2011; 204 (suppl_3):S757-S760. DOI: 10.1093/infdis/jir296
• 10. Le Guenno B, Formenty P, Wyers M, Gounon P, Walker F, Boesch C. Isolation and partial characterisation of a new strain of Ebola virus. The Lancet. 1995; 345 (8960):1271-1274
• 11. Towner JS, Sealy TK, Khristova ML, Albariño CG, Conlan S, Reeder SA, et al. Newly discovered ebola virus associated with hemorrhagic fever outbreak in Uganda. PLoS Pathogens. 2008; 4 (11):e1000212. DOI: 10.1371/journal.ppat.1000212
• 12. Miranda ME, Ksiazek TG, Retuya TJ, Khan AS, Sanchez A, Fulhorst CF, et al. Epidemiology of Ebola (subtype Reston) virus in the Philippines, 1996. The Journal of Infectious Diseases. 1999; 179 (Suppl 1):S115-S119
• 13. Georges AJ, Leroy EM, Renaud AA, et al. Ebola hemorrhagic fever outbreaks in Gabon, 1994-1997: Epidemiologic and health control issues. The Journal of Infectious Diseases. 1999; 179 :S65-S75
• 14. Baize S, Pannetier D, Oestereich L, Rieger T, Koivogui L, Magassouba N, et al. Emergence of Zaire Ebola virus disease in Guinea. The New England Journal of Medicine. 2014; 371 (15):1418-1425. DOI: 10.1056/NEJMoa1404505
• 15. WHO. Disease Outbreak News. 2018a. Available from: https://www.who.int/ebola/situation-reports/drc-2018/en/ [Accessed: 13-01-19]
• 16. Leroy EM, Rouquet P, Formenty P, Souquiere S, Kilbourne A, Froment JM, et al. Multiple Ebola virus transmission events and rapid decline of central African wildlife. Science. 2004a; 303 :387-390
• 17. Heymann DL, Weisfeld JS, Webb PA, Johnson KM, Cairns T, Berquist H. Ebola hemorrhagic fever: Tandala, Zaire, 1977-1978. The Journal of Infectious Diseases. 1980; 142 :372-376
• 18. O’Hearn AE, Voorhees MA, Fetterer DP, Wauquier N, Coomber MR, Bangura J, et al. Serosurveillance of viral pathogens circulating in West Africa. Virology Journal. 2016; 13 (1):163
• 19. Becquart P, Wauquier N, Mahlakõiv T, Nkoghe D, Padilla C, Souris M, et al. High prevalence of both humoral and cellular immunity to Zaire ebolavirus among rural populations in Gabon. PLoS One. 2010; 5 (2):e9126
• 20. Vincent T. Ebola Footprint—Broader Than You Think. Available from: http://oneill.law.georgetown.edu/the-ebola-footprint-broader-than-you-think/
• 21. Olivero J, Fa JE, Real R, Farfan MA, Marquez AN, Vargas JM, et al. Mammalian biogeography and the Ebola virus in Africa. Mammal Review. 2016; 47 :24-37
• 22. Olival KJ, Islam A, Yu M, Anthony SJ, Epstein JH, Khan SA, et al. Ebola virus antibodies in fruit bats, Bangladesh. Emerging Infectious Diseases. 2013; 19 :270-273. DOI: 10.3201/eid1902.120524
• 23. Yuan JF, Zhang YJ, Li JL, Zhang YZ, Wang LF, Shi ZL. Serological evidence of ebolavirus infection in bats, China. Virology Journal. 2012; 9 :236. DOI: 10.1186/1743-422X-9-236
• 24. Peterson AT, Bauer JT, Mills JN. Ecologic and geographic distribution of filovirus disease. Emerging Infectious Diseases. 2004; 10 :40-47. DOI: 10.3201/eid1001.030125
• 25. Rollin PE, Williams RJ, Bressler DS, Pearson S, Cottingham M, Pucak G, et al. Ebola (subtype Reston) virus among quarantined nonhuman primates recently imported from the Philippines to the United States. The Journal of Infectious Diseases. 1999; 179 (Suppl 1):S108-S114
• 26. Wauquier N, Bangura J, Moses L, Humarr Khan S, Coomber M, Lungay V, et al. Understanding the emergence of ebola virus disease in Sierra Leone: Stalking the virus in the threatening wake of emergence. PLOS Currents. 2015; 7
• 27. Ebola virus cases in the United States. Available from: https://en.wikipedia.org/wiki/Ebola_virus_cases_in_the_United_States
• 28. Monath TP. Ecology of Marburg and Ebola viruses: Speculations and directions for the future research. The Journal of Infectious Diseases. 1999; 179 :S127-S138
• 29. Yob JM, Field H, Rashdi AM, Morrissy C, van der Heide B, Rota P, et al. Nipah virus infection in bats (order Chiroptera) in peninsular Malaysia. Emerging Infectious Diseases. 2001; 7 (3):439-441
• 30. Badrane H, Tordo N. Host switching in Lyssavirus history from the Chiroptera to the Carnivora orders. Journal of Virology. 2001; 75 :8096-8104
• 31. Tom Vincent. EBOLA: FIFTEEN YEARS OF SILENCE. 2019. Available from: http://oneill.law.georgetown.edu/ebola-fifteen-years-of-silence/
• 32. Pourrut X, Souris M, Towner JS, Rollin PE, Nichol ST, Gonzalez JP, et al. Large serological survey showing cocirculation of Ebola and Marburg viruses in Gabonese bat populations, and a high seroprevalence of both viruses in Rousettus aegyptiacus. BMC Infectious Diseases. 2009; 9 :159
• 33. Breman JG, Johnson KM, van der Groen G, Robbins CB, Szczeniowski MV, Ruti K, et al. A search for Ebola virus in animals in the Democratic Republic of the Congo and Cameroon: Ecologic, virologic, and sero- logic surveys, 1979-1980. The Journal of Infectious Diseases. 1999; 179 :S139-S147
• 34. Arata AA, Johnson B. Approaches towards studies on potential reservoirs of viral haemorrhagic fever in southern Sudan. In: Pattyn SR, editor. Ebola Virus Haemor- Rhagic Fever. Amsterdam: Elsevier/Netherland biomedical; 1977. pp. 191-202
• 35. Leirs H, Mills JN, Krebs JW, Childs JE, Akaibe D, Woollen N, et al. Search for the Ebola virus reservoir in Kikwit Democratic Republic of the Congo: Reflections on a vertebrate collection. The Journal of Infectious Diseases. 1999; 179 :S155-S163
• 36. Morvan JM, Deubel V, Gounon P, Nakoune E, Barriere P, Murri S, et al. Identification of Ebola virus sequences present as RNA or DNA in organs of terrestrial small mammals of the Central African Republic. Microbes and Infection. 1999; 1 :1193-1201
• 37. Reiter P, Turell M, Coleman R, Miller B, Maupin G, Liz J, et al. Field investigations of an outbreak of Ebola hemorrhagic fever Kikwit Democratic Republic of the Congo, 1995: Arthropod studies. The Journal of Infectious Diseases. 1999; 179 :S148-S154
• 38. Formenty P, Boesch C, Wyers M, Steiner C, Donati F, Dind F, Walker F, Le Guenno B. Ebola virus outbreak among wild chimpanzees living in a rain forest of cote d’Ivoire. The Journal of Infectious Diseases. 1999; 179 (Suppl 1):S120-S126
• 39. Swanepoel R, Leman PA, Burt FJ. Experimental inoculation of plants and animals with Ebola virus. Emerging Infectious Diseases. 1996; 2 :321-325
• 40. Xavier P, Gonzalez JP, Leroy E. Spatial and temporal patterns of Ebola virus antibody prevalence in the putative bat species reservoir. The Journal of Infectious Diseases. 2007; 196 (Suppl 2):S176-S183
• 41. Eric L, Kumulungui B, Pourrut X, Rouquet P, Yaba P, Délicat A, et al. Fruit bats as reservoirs of Ebola virus. Nature. 2005; 438 (7068):575-576
• 42. Caron A, Bourgarel M, Cappelle J, Liégeois F, De Nys HM, Roger F. Ebola virus maintenance: If not (only) bats, what Else? Viruses. 2018; 10 (10):549. DOI: 10.3390/v10100549
• 43. Goldstein T, Anthony SJ, Gbakima A, Bird BH, Bangura J, Tremeau-Bravard A, et al. The discovery of Bombali virus adds further support for bats as hosts of ebolaviruses. Nature Microbiology. 2018; 3 :1084-1089
• 44. Leroy EM, Epelboin A, Mondonge V, Pourrut X, Gonzalez JP, Muyembe-Tamfum JJ, et al. Ebola outbreak associated with direct exposure to fruit bats in Luebo, Democratic Republic of the Congo, 2007. Vector Borne and Zoonotic Diseases. 2009; 9 (6):723-728
• 45. Marí Saéz A, Weiss S, Nowak K, Lapeyre V, Zimmermann F, Düx A, et al. Investigating the zoonotic origin of the west African Ebola epidemic. EMBO Molecular Medicine. 2015; 7 (1):17-23. DOI: 10.15252/emmm.201404792
• 46. Tapanes E, Detwiler KM, Cords M. Bat predation by Cercopithecus monkeys: Implications for zoonotic disease transmission. EcoHealth. 2016; 13 :405-409
• 47. Bermejo M, Illera G, Sabater P. Animals and mushrooms consumed by bonobos (pan paniscus): New records from Lilungu (Ikele), Zaire. International Journal of Primatology. 1994; 15 :879-898
• 48. Leendertz SAJ, Gogarten JF, Düx A, Calvignac-Spencer S, Leendertz FH. Assessing the evidence supporting fruit bats as the primary reservoirs for Ebola viruses. EcoHealth. 2016; 13 (1):18-25
• 49. Olival KJ, Hayman DT. Filoviruses in bats: Current knowledge and future directions. Viruses. 2014; 6 (4):1759-1788. DOI: 10.3390/v6041759
• 50. Gonzalez JP, Pourrut X, Leroy E. Ebolavirus and other filoviruses. Current Topics in Microbiology and Immunology. 2007; 315 :363-387
• 51. Jayme SI, Field HE, de Jong C, Olival KJ, Marsh G, Tagtag AM, et al. Molecular evidence of Ebola Reston virus infection in Philippine bats. Virology Journal. 2015; 12 :107. DOI: 10.1186/s12985-015-0331-3
• 52. Pawęska JT, Jansen van Vuren P, Kemp A, Storm N, Grobbelaar AA, Wiley MR, et al. Marburg virus infection in Egyptian Rousette bats, South Africa, 2013-20141. Emerging Infectious Diseases. 2018 Jun; 24 (6):1134-1137. DOI: 10.3201/eid2406.172165
• 53. de Arellano ER, Sanchez-Lockhart M, Perteguer MJ, Bartlett M, Ortiz M, Campioli P, et al. First evidence of antibodies against Lloviu virus in Schreiber’s bent-winged insectivorous bats demonstrate a wide circulation of the virus in Spain. Viruses. 2019; 11 :360. DOI: 10.3390/v11040360
• 54. Calisher CH, Childs JE, Field HE, Holmes KV, Schountz T. Bats: Important reservoir hosts of emerging viruses. Clinical Microbiology Reviews. 2006; 19 :531-545
• 55. Gonzalez JP, Pourrut X, Leroy E. Ebolavirus and other filoviruses. In: Childs JE, Mackenzie JS, Richt JA, editors. Wildlife and Emerging Zoonotic Diseases: The Biology, Circumstances and Consequences of Cross-Species Transmission. New York, NY, USA: Springer; Heidelberg, Germany; 2007. pp. 363-388
• 56. Allela L, Bourry O, Pouillot R, Délicat A, Yaba P, Kumulungui B, et al. Ebola virus antibody in dogs and human risk. Emerging Infectious Diseases. 2005; 11 (3):385-390
• 57. Ayouba A, Ahuka-Mundeke S, Butel C, Mbala Kingebeni P, Loul S, Tagg N, et al. Extensive serological survey of multiple African non-human primate species reveals low prevalence of IgG antibodies to four Ebola virus species. The Journal of Infectious Diseases. 2019. DOI: 10.1093/infdis/jiz006
• 58. Pigott DM, Golding N, Mylne A, et al. Mapping the zoonotic niche of Ebola virus disease in Africa. eLife. 2014; 3 :e04395
• 59. Paweska JT, Storm N, Grobbelaar AA, Markotter W, Kemp A, Jansen van Vuren P. Experimental inoculation of Egyptian fruit bats ( Rousettus aegyptiacus ) with Ebola virus. Viruses. 2016; 8 (2). pii: E29. DOI: 10.3390/v8020029
• 60. Hijmans RJ, Cameron SE, Parra JL, Jones PG, Jarvis A. Very high-resolution interpolated climate surfaces for global land areas. International Journal of Climatology. 2005; 25 :1965-1978
• 61. Mackensie J, Mills J, editors. Review. In: Wildlife and Emerging Zoonotic Diseases. Springer-Verelag CRC Press. Advances in Virology ch20
• 62. Shaman J, Day JF, Stieglitz M. Drought-induced amplification of Saint Louis encephalitis virus Florida. Emerging Infectious Diseases. 2002; 8 :575-580
• 63. Pourrut X, Kumulungui B, Wittmann T, Moussavou G, Delicat A, Yaba P, et al. The natural history of Ebola virus in Africa. Microbes and Infection. 2005; 7 (7-8):1005-1014
• 64. Gonzalez JP, Souris M, Valdivia-Granda W. Global spread of hemorrhagic fever viruses: Predicting pandemics. Methods in Molecular Biology. 2018; 1604 :3-31. DOI: 10.1007/978-1-4939-6981-4_1

© 2019 The Author(s). Licensee IntechOpen. This chapter is distributed under the terms of the Creative Commons Attribution 3.0 License , which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.

Continue reading from the same book

Edited by Samuel Okware

Published: 12 February 2020

By David A. Schwartz

1227 downloads

By Felix B. He, Krister Melén, Laura Kakkola and Ilkk...

1427 downloads

By Oumar Faye, Cheikh Tidiane Diagne, Amadou Diallo, ...

763 downloads

An official website of the United States government

The .gov means it’s official. Federal government websites often end in .gov or .mil. Before sharing sensitive information, make sure you’re on a federal government site.

The site is secure. The https:// ensures that you are connecting to the official website and that any information you provide is encrypted and transmitted securely.

• Publications
• Account settings

Preview improvements coming to the PMC website in October 2024. Learn More or Try it out now .

• Advanced Search
• Journal List
• J Family Med Prim Care
• v.8(7); 2019 Jul

Ebola virus: A global public health menace: A narrative review

Shamimul hasan.

1 Department of Oral Medicine and Radiology, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India

Syed Ansar Ahmad

2 Department of Oral Surgery, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India

Rahnuma Masood

3 Department of Conservative Dentistry, Faculty of Dentistry, Jamia Millia Islamia, New Delhi, India

Shazina Saeed

4 Department of Amity Institute of Public Health, Amity University, Noida, Uttar Pradesh, India

Ebola virus disease (EVD), a fatal viral hemorrhagic illness, is due to infection with the Ebola virus of the Filoviridae family. The disease has evolved as a global public health menace due to a large immigrant population. Initially, the patients present with nonspecific influenza-like symptoms and eventually terminate into shock and multiorgan failure. There exists no specific treatment protocol for EVD and only supportive and symptomatic therapy is the line of treatment. This review article provides a detailed overview of the Ebola virus; it's clinical and oral manifestations, diagnostic aids, differential diagnosis, preventive aspects, and management protocol.

Ebola, earlier termed as Ebola hemorrhagic fever (EHF), is a critically lethal ailment which primarily affects the humans and nonhuman primates. Ebola virus disease (EVD) occurs due to a virus infection which belongs to the family Filoviridae and genus Ebolavirus .[ 1 ] EVDs has posed diagnostic challenges and has been a universal public health threat since its discovery. While investigating an alleged yellow fever case, Dr. Peter Piot in the year 1976 first detected the disease in Zaire, Africa (presently the Democratic Republic of Congo).[ 2 ] The name “Ebola” was termed as the disease was noticed near the Ebola river in Congo.[ 3 ]

Fruit bats of Pteropodidae family, such as Hypsignathus monstrous, Epomops franqueti , and Myonycteris torquata serve as the natural hosts of the EBOV in Africa. Nonhuman primates may develop the infection by eating the partly eaten fruits and may also transmit the infection to humans.[ 4 ] Indian population is an impending threat to EVD, as India falls in the home range of Pteropodidae family of fruit bats.[ 5 ]

Ebola virus transmission primarily takes place through close bodily contact with the infected patient or their fluids, contaminated tissue surfaces, and clothing from alive, infected or deceased individuals. Unsafe traditional burial practices also play a pivotal role in the disease transmission.[ 6 ] There is documented evidence regarding the sexual mode of disease transmission, although transmission through the air is unlikely.[ 7 ]

EVD present with bizarre and atypical manifestations mimicking other viral diseases, especially in the initial disease phase. Constitutional symptoms, such as fever, myalgia, headache, vomiting, and diarrhea are the early presenting features. Hemorrhagic rash, internal and external bleeding are usually the warning manifestations in the late stages.[ 8 ] Bleeding from the body apertures is a distinguishing EVD manifestation.[ 9 ] Gum bleeding, odynophagia, and atypical oral manifestations constitute the oral features of EVD.[ 10 ]

Till date, there is no precise antiviral management or vaccination for EVD. The management protocol mainly relies on supportive and symptomatic therapy, along with monitoring coagulopathies and multiorgan dysfunction.[ 2 ]

The World Health Organization (WHO) affirmed the EVD outbreak as a “Public Health Emergency of International Concern” on August 8 th , 2014.[ 5 ]

With the enormous immigrant population, India is estimating the likelihood of a probable EVD outbreak. The Ministry of Health and Family Welfare, Government of India, in collaboration with other agencies has appraised the situation and recommended travel instructions by air, land, and sea and health care professionals.[ 11 ]

The virus belongs to the Ebola virus genus, Filoviridae family, and Mononegavirales order.[ 12 ] The genus Ebolavirus includes the following species- Zaire ebolavirus (EBOV), Reston ebolavirus (RESTV), Bundibugyo ebolavirus (BDBV), Taï Forest ebolavirus (TAFV), Sudan ebolavirus (SUDV), and the newly identified Bombali ebolavirus (BOMV).[ 13 ] Except for exclusive identification of RESTV in the Philippines, all the other species causes endemic West African EVD.[ 14 ]

EBOV responsible for the EHF causes the highest human mortality (57%–90%), followed by SUDV (41%–65%) and Bundibugyo virus (40%). TAFV has caused only two nonlethal human infections to date, whereas RESTV causes asymptomatic human infections.[ 15 ]

Figure 1 shows the taxonomy of Ebola virus.

Taxonomy of Ebola virus

Transmission

Based on the Centers for Disease Control and Prevention (CDC) classification, Ebola virus is considered as a biosafety level 4 and category A bioterrorism pathogen with an immense likelihood for massive nationwide transmission.[ 16 ]

Source of Infection

Intimate physical contact with the patients in the acute disease stages and contact with the blood/fluids from the dead individuals constitutes the most important modes of transmission.[ 17 ]

The long-established funeral ceremonies in the African countries entail direct handling of the dead bodies, thus significantly contributing to the disease dissemination. Unsafe conventional burial procedures accounted for 68% infected cases in 2014 EVD outburst of Guinea.[ 18 ]

EBOV RNA may be identified for up to a month in rectal, conjunctival, and vaginal discharges and semen specimens may demonstrate the virus presence up to 3 months, thus signifying the presence of EBOV in recuperating patients.[ 14 ] The sexually transmitted case of EVD has been reported between a convalescent patient and close family member. Another study demonstrated a case in a recuperating male patient. The patient's semen specimen tested positive with Ebola viral antigen almost 3 months after the disease onset.[ 19 ]

Asymptomatic EBOV carriers are not infectious and do not have a major role play in the EVD outburst, and the field practice in Western Africa supported this assumption.[ 20 ] However, this presumption was refuted after the documentation of a pioneer asymptomatic carrier case in North Gabon epidemic (1996).[ 21 ]

EBOV has been detected from blood, saliva, semen, and breast milk, while RNA has been isolated from sweat, tears, stool, and on the skin, vaginal, and rectal swabs, thus highlighting that exposure to infected blood and bodily secretions constitute the major means of dissemination.[ 22 ]

Eating uncooked infected animal meat such as bats or chimpanzees account significantly to oral EVD transmission, especially in the African countries.[ 23 ] The demonstration of the Ebola virus in the Filipino pigs in 2008 triggered the likelihood of an extensive range of possible animal hosts.[ 24 ]

EVD dissemination has also been reported with hospital-acquired infections, particularly in areas with poor hygiene conditions. The infected needles usage was responsible for the 1976 EVD outbreak in Sudan and Zaire.[ 25 , 26 ] Improper hygiene and sterilization were the crucial factors for the 1967 Yambuku EVD outburst.[ 27 ]

EVD dissemination may also occur through the inanimate materials with infected body secretions (fomites).[ 19 ] However, disease transmission through the airborne and droplet infection is ambiguous.[ 10 ]

Figure 2 shows the primary and secondary transmission of disease.

Primary and secondary transmission

Table 1 depicts the possible routes of transmission.

Possible routes of transmission

Epidemiology

The vast majority of EVD cases and outbursts have been endemic to African continent ever since the disease detection in 1976,[ 28 ] and 36 such outbreaks have occurred in six African countries.[ 29 ]

Table 2 shows Ebola epidemiological outbreaks between 1976 and 2014.

Ebola outbreaks between 1976 and 2014 (Adapted from WHO 2014)

UVRI: Uganda Virus Research Institute; CDC: Centers for Disease Control and Prevention

The 2014–2016 EVD started in South East Guinea rural surroundings and eventually became a global public health menace by rapidly disseminating to urban localities and other countries.[ 28 ]

Figure 3 depicts the geographical distribution of Ebola virus disease.

Geographic distribution of Ebola virus disease outbreaks

The conducive environmental surroundings of the African continent facilitate EVD endemicity. However, intermittent imported Ebola cases have also been noticed in United States, United Kingdom, Canada, Spain, and Thailand.[ 30 , 31 ]

Figure 4 depicts the distribution of Ebola virus disease in West African Countries.

Distribution of Ebola virus disease in West African Countries

Out of the unparalleled globally reported 28,616 cases and 11,310 casualties, Liberia accounted for almost 11,000 cases and over 4,800 deaths.[ 32 ]

Table 3 shows the statistics of the 2014–16 West African outbreak.

Statistics of 2014-16 West African outbreak

Pathogenesis

Ebola viruses penetrate the human body through mucous membranes, skin lacerations/tear, close contact with infected patients/corpse, or by direct parental dissemination.[ 33 ] EBOV has a predilection to infect various cells of immune system (dendritic cells, monocytes, and macrophages), endothelial and epithelial cells, hepatocytes, and fibroblasts where it actively replicates by gene modulation and apoptosis and demonstrate significantly high viremia.[ 34 ] The virus reaches the regional lymph nodes causing lymphadenopathy and hematogenous spread to the liver and spleen promote an active inflammatory response.[ 35 ] Release of chemical mediators of inflammation (cytokines and chemokines) causes a dysregulated immune response by disrupting the vasculature system harmony, eventually causing disseminated intravascular coagulation and multiple organ dysfunction.[ 36 ]

Figure 5 demonstrates the pathogenesis of Ebola virus disease.

Pathogenesis of Ebola virus disease

Clinical Features

Due to the bizarre and atypical manifestations in the initial phase, mimicking dengue fever, typhoid fever, malaria, meningococcemia, and other bacterial infections, EVD poses diagnostic dilemmas.[ 37 ]

The incubation period ranges from 2 to 21 days. However, symptoms usually develop 8–11 days following infection.[ 38 , 39 ]

The initial disease phase is represented by constitutional symptoms.[ 40 ] High-grade fever of >38 o C is the most frequently reported symptom (85–95%), followed by other vague symptoms such as general malaise (85–95%), headaches (52–74%), dysphagia, sore throat (56–58%), and dry cough.[ 41 , 42 ] The progressively advanced disease is accompanied by abdominal pain (62–68%), myalgia (50–79%), nausea, vomiting, and diarrhea (84–86%).[ 41 ]

Variety of hemorrhagic manifestations forms an integral component of the late disease phase.[ 38 ] Gastrointestinal tract bleeding manifests as petechiae, hematuria, melena, conjunctival bleeding, contusion, or intraperitoneal bleeding. Mucous membrane and venipuncture site bleeding, along with excess clot formation may also occur. As the features advances with time, the patients experience dehydration, confusion, stupor, hypotension, and multiorgan dysfunction, resulting in fulminant shock and ultimately death.[ 43 , 44 ]

Maculopapular exanthema constitutes a characteristic manifestation of all Filovirus infection, including EVD.[ 45 ] The rash usually appears during the 5 th to 7 th day of disease and occur in 25–52% of patients in the past EVD outbreaks.[ 46 ]

Table 4 shows the clinical manifestations of Ebola virus disease.

Clinical manifestations of Ebola virus disease

Although EVD has a number of similar features with other viral hemorrhagic fevers (e.g. dengue), there are differences that set them apart.

Table 5 depicts the differentiating features of the Ebola virus and dengue virus infection.

Differentiating features of Ebola and dengue virus infection

Orofacial features

Gum bleeding, atypical mucosal lesions, and odynophagia comprise the distinctive oral manifestations. Epistaxis (nasal bleed), bleeding from venipuncture sites, conjunctivitis, and cutaneous exanthema are the other manifestations.[ 9 ] Bleeding tendencies and gum bleeding is not seen in asymptomatic or initial EBOV patients reporting to the dental hospital.

EVD dissemination in the field of oral and dental health may appear nonsignificant; although, probable situations which may pose a risk to dental health professional have been appraised by Samaranayake et al. [ 21 ] and Galvin et al. [ 10 ]

Table 6 depicts the various orofacial manifestations of Ebola virus disease

Orofacial manifestations of Ebola virus disease

EVD patients usually demonstrate altered laboratory parameters based on the stage of the disease.

Table 7 shows the laboratory findings in Ebola virus disease.

Laboratory findings in Ebola virus disease

The WHO (2014) recommended the sample collection of whole blood or oral swab at suitable centres called Ebola treatment centers.[ 47 ] Reverse transcriptase polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA) are the most frequently utilized tests for laboratory affirmation of the EVD.[ 43 ] RT-PCR is capable of detecting viral RNA in the blood samples of infected patients immediately after the commencement of signs and symptoms,[ 42 , 48 ] has a high sensitivity (up to 100%), and gives results within 1–2 days in cases of epidemics. ELISA detects the immunoglobulins G and M in samples of infected patients, has a low sensitivity (91%) and is not suitable for initial affirmation during an outbreak.[ 42 , 49 ]

The most imperative strategy in EVD is to avert the vulnerable population from getting infected and limit the transmission. These preventive strategies entail intensive and rigorous endeavors from the Government, public health amenities, medical units, and personals.[ 50 ]

The most essential aspect to curb EVD transmission is to avert direct bodily contact with infected individuals and their body fluids.[ 51 ]

Health caregivers are extremely vulnerable and experience an augmented professional threat for EVD.[ 52 ] Thus, scrupulous adherence to the universal infection control measures is fundamental in all the hospitals, laboratories, and other health care services.[ 53 ] The U.S. CDC has advocated the appropriate use of various personal protective equipment as a mandate for health care professionals.[ 50 ]

The risk of rapid importation of Ebola virus into human beings can be prevented by averting the direct bush meat and bats contact.[ 54 ]

Unsafe traditional burial procedures, especially in the African continent significantly contributed to the EVD transmission. Hence, it is essential to practice safe and guarded funeral rituals to prevent the disease spread.[ 55 ]

WHO recommends the implementation of safe sex practices to combat the sexual transmission of EVD. Strict abstinence or proper and regular condom use in male EVD survivors at least for a period of 12 months of the symptom onset or until their semen has twice tested negative should be followed.[ 56 ]

Dental health care personals are extremely susceptible to EVD as they are in regular contact with blood and saliva during the routine diagnostic procedures. There is no documented case of EVD through saliva till date. A study on the identification of EBOV in oral fluids affirmed that patients presenting with demonstrable serum levels of EBOV RNA also exhibit identifiable salivary levels.[ 57 ] The incubation period for all body fluids including saliva is 21 days; hence, oral health personals are vulnerable to develop the disease if universal infection control protocol is not followed.[ 58 ]

Table 8 demonstrates the various infection control measures to prevent the Ebola virus spread.

Infection control measures to prevent Ebola virus spread

Box 1 shows the travel guidelines to EBOV affected regions.

Shows the UK Travel guidelines to EBV infested regions.

Till date, there is no precise antiviral management or vaccination for EVD.[ 51 ] The management protocol mainly relies on supportive and symptomatic therapy. Public health strategies emphasizing on epidemiological surveillance, contact tracing, and quarantine of the patient have been recommended to combat the dissemination of EVD.[ 59 ]

Rehydration, adequate nourishment, analgesics, and blood transfusion form a keystone supportive treatment of EVD patient.[ 60 ] Intravenous fluids and oral rehydration solution endow with proper electrolytes substitute and maintain the intravascular volume. Unrelenting vomiting and diarrhea are taken care of by the use of antiemetics and antidiarrheal drugs.[ 35 , 60 , 61 ] Suspected cases of secondary bacterial infections and septicemia are best managed by the use of prophylactic antibiotic regimen (third generation I.V. cephalosporins).[ 62 ] Concurrent parasitic coinfections may also be seen and require prompt investigations and management.[ 63 ]

A number of investigative clinical trials emphasizing on the development of vaccine, antibody therapies, and antiviral drugs have been conducted for EVD.[ 64 ]

Table 9 shows experimental treatment for Ebola virus disease.

Experimental treatment for Ebola virus disease

Various clinical trials in Africa, Europe, and the United States suggest that Ebola vaccines are in various development stages (Phase I–III). A number of candidate vaccines employ diverse platforms, including recombinant viral vectors (most evolved vaccine candidate), DNA vaccines, inactivated viral particles, subunit proteins, recombinant proteins, and virus-like particles. Example of viral vectors expressing ebolavirus glycoproteins include recombinant simian adenovirus (cAd3), recombinant vaccinia virus, recombinant human adenovirus (Ad26), and a live vesicular stomatitis virus used alone or in prime-booster regimens.[ 65 ]

However, Ebola virus having the glycosylated surface proteins and preferentially infecting the immune cells impedes the development of an effective vaccine.[ 66 ]

Dental Management

Dental health care professionals in Europe have not encountered a case of EVD so far. However, health care personals (including dental surgeons) are more prone to EVD while treating patients in West or sub-Saharan Africa. Dental professionals are more likely to encounter asymptomatic EVD patients or those with early-stage vague symptoms.[ 27 ]

Individuals with a travel history to Ebola endemic regions, but with no direct intimate contact with the disease fall in the low-risk category and may undergo any medical/dental health care procedures without restrictions. However, all the nonessential procedures should be postponed for 21 days in individuals with direct exposure to the virus. The regional Health Service Executive Department of Public Health needs to be notified when the exposed patient's treatment cannot be deferred or controlled with pharmacotherapy.[ 10 ]

EVD has emerged as a significant global public health menace due to multiple disease outbreaks in the last 25 years. Recent advancements are being carried out in the form of effective Ebola virus vaccine and anti-Ebola virus drugs. However, rapid geographic dissemination, nonspecific clinical presentation, lack of vaccine, and specific diagnostic test are the possible challenges to combat this dreaded public health menace.

Financial support and sponsorship

Conflicts of interest.

There are no conflicts of interest.

Home — Essay Samples — Nursing & Health — Infectious Diseases — Ebola Virus

Essays About Ebola Virus

Ebola virus essay topics and outline examples, essay title 1: unmasking ebola: origins, transmission, and global response.

Thesis Statement: This essay provides an in-depth analysis of the Ebola virus, including its origins, modes of transmission, symptoms, and the global efforts in containing and managing Ebola outbreaks.

• Understanding Ebola: History, Types, and the Zaire Ebola Virus
• Transmission and Symptoms: How Ebola Spreads and Its Impact on the Human Body
• Outbreaks and Epidemics: Notable Ebola Outbreaks and Their Consequences
• Global Response: International Organizations, Research, and Medical Interventions
• Lessons Learned: Preparing for Future Ebola Outbreaks and Emerging Diseases
• Conclusion: The Ongoing Battle Against Ebola and Infectious Disease Preparedness

Essay Title 2: Ebola's Socioeconomic Impact: Health Systems, Communities, and Resilience

Thesis Statement: This essay explores the broader socioeconomic implications of Ebola outbreaks, examining their impact on healthcare systems, affected communities, and the resilience strategies employed in response to the crisis.

• Healthcare Infrastructure: Vulnerabilities and Challenges During Ebola Outbreaks
• Community Resilience: Coping Strategies and Local Responses to Ebola
• Economic Consequences: Impact on Livelihoods, Trade, and Economic Stability
• Psychosocial Effects: Stigma, Trauma, and Mental Health Considerations
• Global Aid and Assistance: International Support for Affected Regions
• Recovery and Rebuilding: Post-Ebola Rehabilitation and Strengthening Systems
• Conclusion: Beyond the Epidemic - Long-term Recovery and Strengthening Resilience

Essay Title 3: Ebola Vaccines and Therapeutics: Advances, Challenges, and Future Prospects

Thesis Statement: This essay delves into the development of Ebola vaccines and therapeutics, discussing recent advancements, challenges in deployment, and the potential for future innovations in combating Ebola.

• The Race for a Vaccine: Historical Context and the Quest for Immunization
• Therapeutics and Treatment: Experimental Drugs, Blood Plasma, and Supportive Care
• Vaccine Development: Progress in Vaccine Trials and Their Efficacy
• Challenges in Deployment: Ethical Considerations, Access, and Distribution
• Future Prospects: Potential Innovations in Ebola Prevention and Treatment
• Global Health Security: Ebola Preparedness and Pandemic Response
• Conclusion: Advancing Science and Preparedness in the Fight Against Ebola

Evaluation of The Issues Related to The Ebola Virus

Assessment of the ebola virus as a severe problem and ways to stop the disease, made-to-order essay as fast as you need it.

Each essay is customized to cater to your unique preferences

+ experts online

Review on African Virus Ebola

The main problems and suggestions regarding the spread of the ebola disease in africa, the importance of community engagement in eradication of the ebola virus, let us write you an essay from scratch.

• 450+ experts on 30 subjects ready to help
• Custom essay delivered in as few as 3 hours

Relevant topics

• Yellow Fever
• Infectious Disease
• Dengue Fever

By clicking “Check Writers’ Offers”, you agree to our terms of service and privacy policy . We’ll occasionally send you promo and account related email

No need to pay just yet!

We use cookies to personalyze your web-site experience. By continuing we’ll assume you board with our cookie policy .

• Instructions Followed To The Letter
• Deadlines Met At Every Stage
• Unique And Plagiarism Free

Andre Cardoso

How Our Paper Writing Service Is Used

We stand for academic honesty and obey all institutional laws. Therefore EssayService strongly advises its clients to use the provided work as a study aid, as a source of ideas and information, or for citations. Work provided by us is NOT supposed to be submitted OR forwarded as a final work. It is meant to be used for research purposes, drafts, or as extra study materials.

Gombos Zoran

Susan Devlin

Look up our reviews and see what our clients have to say! We have thousands of returning clients that use our writing services every chance they get. We value your reputation, anonymity, and trust in us.

Finished Papers

Our Professional Writers Are Our Pride

EssayService boasts its wide writer catalog. Our writers have various fields of study, starting with physics and ending with history. Therefore we are able to tackle a wide range of assignments coming our way, starting with the short ones such as reviews and ending with challenging tasks such as thesis papers. If you want real professionals some of which are current university professors to write your essays at an adequate price, you've come to the right place! Hiring essay writers online as a newcomer might not be the easiest thing to do. Being cautious here is important, as you don't want to end up paying money to someone who is hiring people with poor knowledge from third-world countries. You get low-quality work, company owners become financial moguls, and those working for such an essay writing service are practically enduring intellectual slavery. Our writing service, on the other hand, gives you a chance to work with a professional paper writer. We employ only native English speakers. But having good English isn't the only skill needed to ace papers, right? Therefore we require each and every paper writer to have a bachelor's, master's, or Ph.D., along with 3+ years of experience in academic writing. If the paper writer ticks these boxes, they get mock tasks, and only with their perfect completion do they proceed to the interview process.

When you write an essay for me, how can I use it?

Essays service custom writing company - the key to success.

Quality is the most important aspect in our work! 96% Return clients; 4,8 out of 5 average quality score; strong quality assurance - double order checking and plagiarism checking.

Customer Reviews

Our writers always follow the customers' requirements very carefully

Read what our clients have to say about our writing essay services!

"Essay - The Challenges of Black Students..."

Write essay for me and soar high!

We always had the trust of our customers, and this is due to the superior quality of our writing. No sign of plagiarism is to be found within any content of the entire draft that we write. The writings are thoroughly checked through anti-plagiarism software. Also, you can check some of the feedback stated by our customers and then ask us to write essay for me.

Affiliate program

Refer our service to your friend and receive 10% from every order

Jam Operasional (09.00-17.00)

+62 813-1717-0136 (Corporate)                                      +62 812-4458-4482 (Recruitment)

In the order page to write an essay for me, once you have filled up the form and submitted it, you will be automatically redirected to the payment gateway page. There you will be required to pay the entire amount for taking up the service and writing from my experts. We will ask you to pay the entire amount before the service as that gives us an assurance that you will come back to get the final draft that we write and lets us build our trust in you to write my essay for me. It also helps us to build up a mutual relationship with you while we write, as that would ease out the writing process. You are free to ask us for free revisions until you are completely satisfied with the service that we write.

Perfect Essay

Can I Trust You With Other Assignments that aren't Essays?

The best way to complete a presentation speech is with a team of professional writers. They have the experience, the knowledge, and ways to impress your prof. Another assignment you can hire us for is an article review. Evaluating someone's work with a grain of salt cannot be easy, especially if it is your first time doing this. To summarize, article reviews are a challenging task. Good that you've found our paper service and can now drop your worries after placing an order. If reading 100-page-long academic articles and digging into every piece of information doesn't sound like something you'd want to do on a Sunday night, hire our essay writing company to do your research proposal. Are you struggling with understanding your professors' directions when it comes to homework assignments? Hire professional writers with years of experience to earn a better grade and impress your parents. Send us the instructions, and your deadline, and you're good to go. We're sure we have a professional paper writer with the skills to complete practically any assignment for you. We only hire native English speakers with a degree and 3+ years of experience, some are even uni professors.

Constant customer Assistance

Is a “rare breed” among custom essay writing services today.

All the papers delivers are completely original as we check every single work for plagiarism via advanced plagiarism detection software. As a double check of the paper originality, you are free to order a full plagiarism PDF report while placing the order or afterwards by contacting our Customer Support Team.

Being tempted by low prices and promises of quick paper delivery, you may choose another paper writing service. The truth is that more often than not their words are hollow. While the main purpose of such doubtful companies is to cash in on credulity of their clients, the prime objective of is clients’ satisfaction. We do fulfill our guarantees, and if a customer believes that initial requirements were not met or there is plagiarism found and proved in paper, they can request revision or refund. However, a refund request is acceptable only within 14 days of the initial deadline.

Our paper writing service is the best choice for those who cannot handle writing assignments themselves for some reason. At , you can order custom written essays, book reviews, film reports, research papers, term papers, business plans, PHD dissertations and so forth. No matter what academic level or timeframe requested is – we will produce an excellent work for you!

Customers usually want to be informed about how the writer is progressing with their paper and we fully understand that – he who pays the piper calls the tune. Therefore, with you have a possibility to get in touch with your writer any time you have some concerns or want to give additional instructions. Our customer support staff is there for you 24/7 to answer all your questions and deal with any problems if necessary.

Of course, the best proof of the premium quality of our services is clients’ testimonials. Just take a few minutes to look through the customer feedback and you will see that what we offer is not taking a gamble.

is a company you can trust. Share the burden of academic writing with us. Your future will be in safe hands! Buy essays, buy term papers or buy research papers and economize your time, your energy and, of course, your money!

Finish Your Essay Today! EssayBot Suggests Best Contents and Helps You Write. No Plagiarism!

Online essay writing service to reach academic success..

Are you looking for the best essay writing service to help you with meeting your academic goals? You are lucky because your search has ended. is a place where all students get exactly what they need: customized academic papers written by experts with vast knowledge in all fields of study. All of our writers are dedicated to their job and do their best to produce all types of academic papers of superior quality. We have experts even in very specific fields of study, so you will definitely find a writer who can manage your order.

Diane M. Omalley

10 question spreadsheets are priced at just .39! Along with your finished paper, our essay writers provide detailed calculations or reasoning behind the answers so that you can attempt the task yourself in the future.

Useful Links

• Request a call back
• Write For Us

How to Write an Essay For Me

EssayService strives to deliver high-quality work that satisfies each and every customer, yet at times miscommunications happen and the work needs revisions. Therefore to assure full customer satisfaction we have a 30-day free revisions policy.

offers a great selection of professional essay writing services. Take advantage of original, plagiarism-free essay writing. Also, separate editing and proofreading services are available, designed for those students who did an essay and seek professional help with polishing it to perfection. In addition, a number of additional essay writing services are available to boost your customer experience to the maximum!

Advanced writer

Add more quality to your essay or be able to obtain a new paper within a day by requesting a top or premium writer to work on your order. The option will increase the price of your order but the final result will be totally worth it.

Top order status

Every day, we receive dozens of orders. To process every order, we need time. If you’re in a great hurry or seek premium service, then choose this additional service. As a result, we’ll process your order and assign a great writer as soon as it’s placed. Maximize your time by giving your order a top status!

SMS updates

Have you already started to write my essay? When it will be finished? If you have occasional questions like that, then opt-in for SMS order status updates to be informed regarding every stage of the writing process. If you’re pressed for time, then we recommend adding this extra to your order.

Plagiarism report

Is my essay original? How do I know it’s Turnitin-ready? Very simple – order us to attach a detailed plagiarism report when work is done so you could rest assured the paper is authentic and can be uploaded to Turnitin without hesitating.

1-page summary

World’s peace isn’t riding on essay writing. If you don’t have any intent on reading the entire 2000-word essay that we did for you, add a 1-page summary to your order, which will be a short overview of your essay one paragraph long, just to be in the loop.

• Words to pages
• Pages to words

A writer who is an expert in the respective field of study will be assigned

You are going to request writer Estevan Chikelu to work on your order. We will notify the writer and ask them to check your order details at their earliest convenience.

The writer might be currently busy with other orders, but if they are available, they will offer their bid for your job. If the writer is currently unable to take your order, you may select another one at any time.

Please place your order to request this writer

Our team of writers is native English speakers from countries such as the US with higher education degrees and go through precise testing and trial period. When working with EssayService you can be sure that our professional writers will adhere to your requirements and overcome your expectations. Pay your hard-earned money only for educational writers.

Original Drafts

Professional essay writing services

Here you have an Expository Essay on Ebola Virus, Lets start with the introduction. Introduction. The Ebola virus is one of the most dangerous and deadly viruses known to humans. The Ebola epidemic since its discovery in 1976 came from the Democratic Republic of Congo, formerly known as Zaire, but the largest Ebola outbreak known to date is still ongoing at the time of writing, in the West Africa.

Free example of expository essay about Ebola virus: Ebola was first discovered 1976 in Africa, on the banks of the Ebola river, after which the virus has been named... AI Tools; Writing; Text editing; Coding; ... More from Expository Essay Examples and Samples. Nov 23 2023. Why Is Of Mice And Men Banned. 5 min read. Nov 07 2023. Pride and ...

This chapter presents a review of what is known about the natural history of the Ebolaviruses in Central and West Africa as well as in the Philippines. All the previous hypotheses on the natural cycle of Ebolavirus are revisited. Also, the main factors driving the virus natural cycle are summarized for the different ecosystems where the Ebolavirus is known to have emerged, including the virus ...

In 2014, Ebola hemorrhagic fever caused an outbreak in West Africa that officially ended in 2016. The Centers for Disease Control and Prevention (CDC) says, "Ebola is a rare and deadly disease caused by infection with one of the Ebola virus species" ("Ebola (Ebola Virus Disease)").

1. Introduction. The Ebola virus (EBOV) belongs to the family Filoviridae, which is a group of single-stranded RNA viruses that can lead to severe hemorrhagic fever in humans and other primates. This virus is an extremely infectious virus with a high rate of fatalities (up to 90%) which makes it one of the deadliest viral diseases (Ebola virus ...

Introduction. Ebola, earlier termed as Ebola hemorrhagic fever (EHF), is a critically lethal ailment which primarily affects the humans and nonhuman primates. Ebola virus disease (EVD) occurs due to a virus infection which belongs to the family Filoviridae and genus Ebolavirus . [ 1] EVDs has posed diagnostic challenges and has been a universal ...

Fruit bats are considered to be a putative reservoir of Ebola virus in Central Africa after 2004; In 2009, several non-human primate epizootic are reported; 1976 was the first emerging events and ...

Ebola Virus Is A Serious Virus Disease. Ebola Virus is a serious transmitted disease by both humans and animals. The disease first appeared in 1976 in 2 simultaneous outbreaks, one in Nzara, Sudan, and the other in Yambuku, Democratic Republic of Congo. The latter occurred in a village near the Ebola River, from which the virus received its name.

Ebola Virus Essay Topics and Outline Examples Essay Title 1: Unmasking Ebola: Origins, Transmission, and Global Response. Thesis Statement: This essay provides an in-depth analysis of the Ebola virus, including its origins, modes of transmission, symptoms, and the global efforts in containing and managing Ebola outbreaks.

Expository Essay On Ebola Virus | Best Writing Service. 1 (888)814-4206 1 (888)499-5521.

Essays service custom writing company - The key to success. Quality is the most important aspect in our work! 96% Return clients; 4,8 out of 5 average quality score; strong quality assurance - double order checking and plagiarism checking. Posted on 12 Juli 2022 by harriz 481. ID 11801.

Write An Expository Essay On Ebola Virus. The experts well detail out the effect relationship between the two given subjects and underline the importance of such a relationship in your writing. Our cheap essay writer service is a lot helpful in making such a write-up a brilliant one.

Expository Essay On Ebola Virus. Hire a Writer. 347. Customer Reviews. Nursing Business and Economics Management Marketing +130. 19 Customer reviews. 4093 Orders prepared.

Read what our clients have to say about our writing essay services! Go through some of the priceless words stated down by our customers regarding our writing service: +1 (888) 985-9998. 407. Customer Reviews. 784. Finished Papers. Hire writers. Plagiarism report. .99.

Expository Essay On Ebola Virus - Benny. 2191 Orders prepared. Your Price:.40 per page. 100% Success rate ... Expository Essay On Ebola Virus, Essay On Be True To Yourself, Thesis Statement For Time Travel, Essay Samples Outlines, Sample Application Letter For Radiologic Technologist, Essay On The Value Of Human Life, Rural Development Research ...

Susanne. Expository Essay On Ebola Virus. Write My Essay Service Helps You Succeed! Being a legit essay service requires giving customers a personalized approach and quality assistance. We take pride in our flexible pricing system which allows you to get a personalized piece for cheap and in time for your deadlines.

Some low-skilled writers will still send you an essay file, but the text will not meet the required parameters. is the best essay writing service because we provide guarantees at all stages of cooperation. Our polite managers will answer all your questions and help you determine the details. We will sign a contract with you so that you can be ...

Write An Expository Essay On Ebola Virus: Anne. User ID: 102732. Megan Sharp #12 in Global Rating Degree: Bachelor's. Previous. 1(888)814-4206 1(888)499-5521. The reaction paper was written... Level: Master's, University, College, High School, PHD, Undergraduate ...

Expository Essay On The Ebola Virus - 100% Success rate ID 21067 NAVIGATION. Completed orders: 145 ... As we are an honest and well-paying essay writer service, writers come flying our way. Nonetheless, in the writers' community, we are known for our strict selection process. You as a client can be sure that you will be working with the best ...

Expository Essay On The Topic Ebola Virus, Resume Example Fundraisier Non Profit, Examples Of Outlines For Essays Mla, Sacrifices Love Definition Essay, Land Degradation Assessment And Farmer Attitude Towards Land Management Practices Thesis Pdf, College Confidential Why Essays, Essay Writing For Women Wanting To Be Sterilized ...

Expository Essay On The Topic Ebola Virus, Critical Thinking In Nurse Managers, Proofreading Rates, Sales Associate Work Experience Resume Sample, Chemactivity 28 Critical Thinking Questions, Format Thesis Uthm 2017, The Time My Teacher Helped Improve My Reading Skills Essay

Benefits You Get from Our Essay Writer Service. Typically, our authors write essays, but they can do much more than essays. We also offer admissions help. If you are preparing to apply for college, you can get an admission essay, application letter, cover letter, CV, resume, or personal statement from us. Since we know what the admissions ...

If you want your order to be completed by one of the best writers from our essay writing service with superb feedback, choose this option. Your preferred writer. You can indicate a specific writer's ID if you have already received a paper from him/her and are satisfied with it. Also, our clients choose this option when they have a series of ...

• essay analysis
• essay format
• essay online
• essay samples
• essay template
• essay topics

Don’t Drown In Assignments — Hire an Essay Writer to Help!

Does a pile of essay writing prevent you from sleeping at night? We know the feeling. But we also know how to help it. Whenever you have an assignment coming your way, shoot our 24/7 support a message or fill in the quick 10-minute request form on our site. Our essay help exists to make your life stress-free, while still having a 4.0 GPA. When you pay for an essay, you pay not only for high-quality work but for a smooth experience. Our bonuses are what keep our clients coming back for more. Receive a free originality report, have direct contact with your writer, have our 24/7 support team by your side, and have the privilege to receive as many revisions as required.

We have the ultimate collection of writers in our portfolio, so once you ask us to write my essay, we can find you the most fitting one according to your topic. The perks of having highly qualified writers don't end there. We are able to help each and every client coming our way as we have specialists to take on the easiest and the hardest tasks. Whatever essay writing you need help with, let it be astronomy or geography, we got you covered! If you have a hard time selecting your writer, contact our friendly 24/7 support team and they will find you the most suitable one. Once your writer begins the work, we strongly suggest you stay in touch with them through a personal encrypted chat to make any clarifications or edits on the go. Even if miscommunications do happen and you aren't satisfied with the initial work, we can make endless revisions and present you with more drafts ASAP. Payment-free of course. Another reason why working with us will benefit your academic growth is our extensive set of bonuses. We offer a free originality report, title, and reference page, along with the previously mentioned limitless revisions.

What's the minimum time you need to complete my order?

offers three types of essay writers: the best available writer aka. standard, a top-level writer, and a premium essay expert. Every class, or type, of an essay writer has its own pros and cons. Depending on the difficulty of your assignment and the deadline, you can choose the desired type of writer to fit in your schedule and budget. We guarantee that every writer will be a subject-matter expert with proper writing skills and background knowledge across all high school, college, and university subjects. Also, we don’t work with undergraduates or dropouts, focusing more on Bachelor, Master, and Doctoral level writers (yes, we offer writers with Ph.D. degrees!)

Know Us Better

• Knowledge Base
• Referencing Styles
• Know Our Consultance
• Revision and Refund Policy
• Terms Of Use

Our Top Proficient Writers At Your Essays Service

Finished Papers

Standard essay helper

Customer Reviews

Fill up the form and submit

On the order page of our write essay service website, you will be given a form that includes requirements. You will have to fill it up and submit.

Who can help me write my essay?

At the end of the school year, students have no energy left to complete difficult homework assignments. In addition, inspiration is also lacking, so there are only a few options:

• do not write a scientific work;
• write it badly;
• delegate these responsibilities to other people.

Most often, people choose the latter option, which is why companies have appeared on the Internet offering to take full responsibility.

When you visit the site, the managers clarify all the details in order to correctly design the article. They select a person who is well versed in the topic of the report and give him your task.

You will not be able to personally communicate with the writer who will do your work. This is done to ensure that all your personal data is confidential. The client, of course, can make edits, follow the writing of each section and take part in the correction, but it is impossible to communicate with the team.

Do not worry that you will not meet personally with the site team, because throughout the entire cooperation our managers will keep in touch with each client.

We use cookies. By browsing the site, you agree to it. Read more »

How to Order Our Online Writing Services.

There is nothing easier than using our essay writer service. Here is how everything works at :

• You fill out an order form. Make sure to provide us with all the details. If you have any comments or additional files, upload them. This will help your writer produce the paper that will exactly meet your needs.
• You pay for the order with our secure payment system.
• Once we receive the payment confirmation, we assign an appropriate writer to work on your project. You can track the order's progress in real-time through the personal panel. Also, there is an option to communicate with your writer, share additional files, and clarify all the details.
• As soon as the paper is done, you receive a notification. Now, you can read its preview version carefully in your account. If you are satisfied with our professional essay writing services, you confirm the order and download the final version of the document to your computer. If, however, you consider that any alterations are needed, you can always request a free revision. All our clients can use free revisions within 14 days after delivery. Please note that the author will revise your paper for free only if the initial requirements for the paper remain unchanged. If the revision is not applicable, we will unconditionally refund your account. However, our failure is very unlikely since almost all of our orders are completed issue-free and we have 98% satisfied clients.

As you can see, you can always turn to us with a request "Write essay for me" and we will do it. We will deliver a paper of top quality written by an expert in your field of study without delays. Furthermore, we will do it for an affordable price because we know that students are always looking for cheap services. Yes, you can write the paper yourself but your time and nerves are worth more!

Final Paper

Finish Your Essay Today! EssayBot Suggests Best Contents and Helps You Write. No Plagiarism!

Leave a reply cancel reply.

Your email address will not be published. Required fields are marked *

Save my name, email, and website in this browser for the next time I comment.

Megan Sharp

Terms of Use

Privacy Policy

Customer Reviews

is here to help you!

Student years are the best time of one’s life. You are in the prime of your life and hopeful about the bright future ahead. This is the period that leaves the funniest photos, the sweetest memories, and gives you the most faithful friends. However, there is one thing that spoils all the fun – assignment writing. Have you ever struggled to write an essay or prepare a speech only to find that the deadline is getting closer, and the work is not ready yet? Are you desperate for someone to have your paper done? Ordering it online is a really convenient option, but you must be sure that the final product is worth the price. is one of the leading online writing centers that deliver only premium quality essays, term papers, and research papers.

Once you place an order and provide all the necessary instructions, as well as payment, one of our writers will start working on it. Be sure we won’t choose a person to do your paper at random. The writer assigned will hold an academic degree in the respective area of expertise, which makes it possible for him/her to find the relevant information, carry out exhaustive research, and develop a comprehensible and well-organized document. The final product will meet all your specifications regarding the content and formatting style. What is more, you will not have to proofread it for any grammatical or spelling errors, because our professionals have a really good command of the English language.

A standard essay helper is an expert we assign at no extra cost when your order is placed. Within minutes, after payment has been made, this type of writer takes on the job. A standard writer is the best option when you’re on a budget but the deadline isn’t burning. Within a couple of days, a new custom essay will be done for you from the ground up. Unique content, genuine research, spot-on APA/MLA formatting, and peerless grammar are guaranteed. Also, we’ll provide you with a free title page, bibliography, and plagiarism check. With a standard writer, you can count on a quality essay that will live up to all your expectations.

Essays service custom writing company - The key to success

Quality is the most important aspect in our work! 96% Return clients; 4,8 out of 5 average quality score; strong quality assurance - double order checking and plagiarism checking.

Finished Papers

Get Professional Writing Services Today!

Get a free quote from our professional essay writing service and an idea of how much the paper will cost before it even begins. If the price is satisfactory, accept the bid and watch your concerns slowly fade away! Our team will make sure that staying up until 4 am becomes a thing of the past. The essay service is known for providing some of the best writing, editing, and proofreading available online. What are you waiting for? Join our global educational community today!

Look up our reviews and see what our clients have to say! We have thousands of returning clients that use our writing services every chance they get. We value your reputation, anonymity, and trust in us.

Johan Wideroos

Finished Papers

Is my essay writer skilled enough for my draft?

Please enter your email to receive the instructions on how to reset your password.

Compare Properties

How our paper writing service is used.

We stand for academic honesty and obey all institutional laws. Therefore EssayService strongly advises its clients to use the provided work as a study aid, as a source of ideas and information, or for citations. Work provided by us is NOT supposed to be submitted OR forwarded as a final work. It is meant to be used for research purposes, drafts, or as extra study materials.

Customer Reviews

Our Team of Professional Essay Writers

As we are an honest and well-paying essay writer service, writers come flying our way. Nonetheless, in the writers' community, we are known for our strict selection process. You as a client can be sure that you will be working with the best paper writer in the game no matter your subject or the difficulty of the task as all our writers go through testing and have their degrees checked. Only 3% of all applicants are accepted to work with us and even these 3% have a training program and a two-month trial period ahead. We value our reputation and only hire true experts with years of experience in academic writing behind their backs. Nonetheless, being a professional writers service has its challenges. For example, as our employer expectations are high, not all writers can handle the challenge of creating zero-plagiarism essay writing content in a short time frame, so as leading writing services we must keep everything in control.

How Our Essay Service Works

offers a great selection of professional essay writing services. Take advantage of original, plagiarism-free essay writing. Also, separate editing and proofreading services are available, designed for those students who did an essay and seek professional help with polishing it to perfection. In addition, a number of additional essay writing services are available to boost your customer experience to the maximum!

Advanced writer

Add more quality to your essay or be able to obtain a new paper within a day by requesting a top or premium writer to work on your order. The option will increase the price of your order but the final result will be totally worth it.

Top order status

Every day, we receive dozens of orders. To process every order, we need time. If you’re in a great hurry or seek premium service, then choose this additional service. As a result, we’ll process your order and assign a great writer as soon as it’s placed. Maximize your time by giving your order a top status!

SMS updates

Have you already started to write my essay? When it will be finished? If you have occasional questions like that, then opt-in for SMS order status updates to be informed regarding every stage of the writing process. If you’re pressed for time, then we recommend adding this extra to your order.

Plagiarism report

Is my essay original? How do I know it’s Turnitin-ready? Very simple – order us to attach a detailed plagiarism report when work is done so you could rest assured the paper is authentic and can be uploaded to Turnitin without hesitating.

1-page summary

World’s peace isn’t riding on essay writing. If you don’t have any intent on reading the entire 2000-word essay that we did for you, add a 1-page summary to your order, which will be a short overview of your essay one paragraph long, just to be in the loop.

Essay writing help has this amazing ability to save a student’s evening. For example, instead of sitting at home or in a college library the whole evening through, you can buy an essay instead, which takes less than one minute, and save an evening or more. A top grade for homework will come as a pleasant bonus! Here’s what you have to do to have a new 100% custom essay written for you by an expert.

To get the online essay writing service, you have to first provide us with the details regarding your research paper. So visit the order form and tell us a paper type, academic level, subject, topic, number and names of sources, as well as the deadline. Also, don’t forget to select additional services designed to improve your online customer experience with our essay platform.

Once all the form fields are filled, submit the order form that will redirect you to a secure checkout page. See if all the order details were entered correctly and make a payment. Just as payment is through, your mission is complete. The rest is on us!

Enjoy your time, while an online essay writer will be doing your homework. When the deadline comes, you’ll get a notification that your order is complete. Log in to your Customer Area on our site and download the file with your essay. Simply enter your name on the title page on any text editor and you’re good to hand it in. If you need revisions, activate a free 14-30-day revision period. We’ll revise the work and do our best to meet your requirements this time.

Rebecca Geach