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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. .

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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

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Emerging Challenges in Filovirus Infections

Edited by Samuel Ikwaras Okware

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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.

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• 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

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Ebola Virus Disease Analysis Essay

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Gaps in the System that May Contribute to the Spread of Ebola

Strategy for addressing ebola within the structure of the health system, options for financing the strategy.

The Ebola virus disease (EVD) outbreak emerged as a significant threat to the lives and safety of both the countries of West Africa and the overall global community. The deaths of a significant number of citizens of West African countries might have been averted if several systematic and organizational issues have been implemented promptly. Unlike countries of equatorial Africa, West African states had never experienced EVD before 2014 and were unprepared to identify, treat, or epidemic management of the disease (World Health Organization [WHO], 2015a).

The overall underdeveloped and underfinanced system of health care in these countries significantly contributes to the spread of the illness. In particular, the public health system lacks funding, a scientific base, and experts. Also, “ineffective diagnostic and case management services” obstruct the opportunity to detect the first cases of EVD in time and prevent its international spread (Shrivastava, 2016, p. 105). Also, the unproductive cooperation of facilities and organizations at the community level complicates the possibility of united adherence to the same pattern of dealing with an outbreak and threatens the success of the implemented interventions.

Considering the factors that contribute to the spread of EVD in West African countries, the strategy for addressing the disease should be concentrated on the elimination of the identified problems. In general, the overall health care infrastructure of the developing countries has to be improved by means of international support and governmental programs. Firstly, scientific evidence-based health care needs to be advanced, which may be achieved through the attraction of foreign experts and the improvement of educational efforts. Secondly, better management and technology implementation is needed to ensure effective diagnostics and disease management.

For that matter, new laboratories need to be launched, as well as the number of facilities specializing in infectious diseases should be increased. Thirdly, community-based initiatives need to be implemented to ensure sufficient local work on the identification and treatment of EVD.

Fourthly, the countries of Western Africa need to develop an effective preventative program. All countries must be “ready to safely and effectively detect, investigate, manage and report potential Ebola cases” and act within the coordinated guidelines (WHO, 2015b, p. 12). Finally, an effective technology-driven and internationally supported monitoring program is required to ensure virus transmission surveillance (WHO, 2015a). All these steps are aimed at the strategic restructuring of the current health system of the countries significantly inclined to Ebola outbreaks. The implementation of the strategy requires proper financing for the effective achievement of anticipated results.

The issue of Ebola outbreaks in countries with ineffective health care systems imposes significant safety concerns for the whole global community due to the high level of transmission of EVD. Therefore, it is in the interests of international organizations to supply necessary resources for West African countries to enforce the strategy implementation. One of the options to attract financial aid to the region is via the Multi-Partner Trust Fund (WHO, 2015b). Also, the funding might be provided via national donations of the developed countries, as well as the World Bank and CDC fund (WHO, 2016). As for the community-based interventions, the governments of the countries of West Africa need to allocate the necessary budget to ensure effective local work.

Shrivastava, S. R., Shrivastava, P. S., & Ramasamy, J. (2016). Ebola outbreak in West Africa: Bridging the gap between the public health authorities and the community. Iranian Journal of Nursing and Midwifery Research, 21 (1), 105-106.

World Health Organization. (2015a). Factors that contributed to the undetected spread of the Ebola virus and impeded rapid containment . Web.

World Health Organization. (2016). West Africa Ebola outbreak: Funding. Web.

World Health Organization. (2015b). WHO strategic response plan: West Africa Ebola outbreak . Web.

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Essay on the Elusive Natural History of Ebola Viruses

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Essay on Ebola Virus – Narrative essay

Title: We Are Not Winning The War On The Ebola Outbreak!

Introduction My time in Africa highlighted to me just how little we know about the Ebola outbreak and how far it has spread. In my essay I detail the problems that the WHO are having keeping the outbreak contained and eradicating the problem. I also highlight the ways we are losing the fight against Ebola.

Whilst in Africa I couldn’t help but notice how the Ebola virus didn’t appear in isolated cases. What happens is that a village is cleared for having the disease, and then suddenly a lot of people are infected at one time for no discernible reason. It is almost as if someone throws a batch of the disease into the water supply to infect many people at once.

There are a lot of theories about why this is happening. Some say that the water is poisoned–even though tests show it is not. Some are saying the people are being infected on purpose to test vaccines and make money from selling vaccines to aid workers and the WHO. My findings indicate a very different scenario.

The fact is that African families are hiding their infected family members. They hide them mostly through fear of then being isolated from their own community. When one family member is ill, the rest of the family is spurned and even attacked and forced to leave the village and surrounding area.

That is not the only reason why African families are hiding their ill family members. There are some that believe faith in a higher power or native medicine will heal their ill, and many do not trust the health-care workers that are being sent in to help. I watched as doctors, professionals and medical staff were chased out of villages and attacked.

Health and aid workers are being attacked because they look like the bad guys. They take ill people from the village, the ill people die, they are incinerated, and the people in the village never see them again. People are giving up their family members in large trucks to be sent to quarantine, and those people are never seen again. To some African families, the health workers are nothing short of abduction crews removing beloved and ill family members.

Many family members would prefer to die surrounded by the ones they love and not in a WHO medical facility. I also found that a lot of families were distressed at the fact they couldn’t visit their ill family members and how when they gave them up to the WHO they were seeing them for the last time. Key family members have been stricken with the illness, which leaves families without a leader and without any way to make money. The situation is grim to say the least.

Conclusion We cannot accurately predict the spread of the Ebola outbreak and we cannot correctly estimate how many people are still infected. There is no way of knowing exactly how many people are infected because people are going to continue hiding family members that are ill.

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Ebola Virus Disease Outbreaks: Lessons Learned From Past and Facing Future Challenges

Affiliations.

• 1 Support to DTRA Technical Reachback, Battelle Memorial Institute, Columbus, OH 43201, USA.
• 2 Support to DTRA Technical Reachback, Global Systems Engineering (GSE), Alexandria, VA 22312, USA.
• 3 Support to DTRA Technical Reachback, Applied Research Associates (ARA), Albuquerque, NM 87110, USA.
• 4 SME Support to DTRA Technical Reachback, Manta Solutions, Charlottesville, VA 22901, USA.
• 5 Office of the Command Surgeon, U.S. Africa Command, APO, AE 09751, USA.
• 6 Office of Readiness and Response, U.S. Centers for Disease Control and Prevention, Atlanta, GA 30329, USA.
• 7 Technical Reachback, Defense Threat Reduction Agency (DTRA), Fort Belvoir, VA 22060, USA.
• PMID: 38743575
• DOI: 10.1093/milmed/usae204
• Correction To: Ebola Virus Disease Outbreaks: Lessons Learned From Past and Facing Future Challenges. [No authors listed] [No authors listed] Mil Med. 2024 Jun 24:usae328. doi: 10.1093/milmed/usae328. Online ahead of print. Mil Med. 2024. PMID: 38910371 No abstract available.

Introduction: The purpose of this review is to examine African Ebola outbreaks from their first discovery to the present, to determine how the medical and public health response has changed and identify the causes for those changes. We sought to describe what is now known about the epidemiology and spread of Ebola virus disease (EVD) from the significant outbreaks that have occurred and outbreak control methods applied under often challenging circumstances. Given the substantial role that the U.S. Government and the U.S. DoD have played in the 2014 to 2016 West African Ebola outbreak, the role of the DoD and the U.S. Africa Command in controlling EVD is described.

Materials and methods: A descriptive method design was used to collect and analyze all available Ebola outbreak literature using the PubMed database. An initial literature search was conducted by searching for, obtaining, and reading original source articles on all major global Ebola outbreaks. To conduct a focused search, we used initial search terms "Ebola outbreak," "Ebola virus disease," "Ebola response," "Ebola countermeasures," and also included each country's name where Ebola cases are known to have occurred. From the 4,673 unique articles obtained from this search and subsequent article title review, 307 articles were identified for potential inclusion. Following abstract and article review, 45 original source articles were used to compile the history of significant Ebola outbreaks. From this compilation, articles focused on each respective subsection of this review to delineate and describe the history of EVD and response, identifying fundamental changes, were obtained and incorporated.

Results: We present known Ebola virus and disease attributes, including a general description, seasonality and location, transmission capacity, clinical symptoms, surveillance, virology, historical EVD outbreaks and response, international support for Ebola outbreak response, U.S. DoD support, medical countermeasures supporting outbreak response, remaining gaps to include policy limitations, regional instability, climate change, migration, and urbanization, public health education and infrastructure, and virus persistence and public awareness.

Conclusions: The health and societal impacts of EVD on Africa has been far-reaching, with about 35,000 cases and over 15,000 deaths, with small numbers of cases spreading globally. However, the history of combatting EVD reveals that there is considerable hope for African nations to quickly and successfully respond to Ebola outbreaks, through use of endemic resources including Africa CDC and African Partner Outbreak Response Alliance and the U.S. Africa Command with greater DoD reachback. Although there remains much to be learned about the Ebola virus and EVD including whether the potential for novel strains to become deadly emerging infections, invaluable vaccines, antivirals, and public health measures are now part of the resources that can be used to combat this disease.

Published by Oxford University Press on behalf of the Association of Military Surgeons of the United States 2024. This work is written by (a) US Government employee(s) and is in the public domain in the US.

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How to Write an Expository Essay | Structure, Tips & Examples

Published on July 14, 2020 by Jack Caulfield . Revised on July 23, 2023.

“Expository” means “intended to explain or describe something.” An expository essay provides a clear, focused explanation of a particular topic, process, or set of ideas. It doesn’t set out to prove a point, just to give a balanced view of its subject matter.

Expository essays are usually short assignments intended to test your composition skills or your understanding of a subject. They tend to involve less research and original arguments than argumentative essays .

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Table of contents

When should you write an expository essay, how to approach an expository essay, introducing your essay, writing the body paragraphs, concluding your essay, other interesting articles, frequently asked questions about expository essays.

In school and university, you might have to write expository essays as in-class exercises, exam questions, or coursework assignments.

Sometimes it won’t be directly stated that the assignment is an expository essay, but there are certain keywords that imply expository writing is required. Consider the prompts below.

The word “explain” here is the clue: An essay responding to this prompt should provide an explanation of this historical process—not necessarily an original argument about it.

Sometimes you’ll be asked to define a particular term or concept. This means more than just copying down the dictionary definition; you’ll be expected to explore different ideas surrounding the term, as this prompt emphasizes.

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An expository essay should take an objective approach: It isn’t about your personal opinions or experiences. Instead, your goal is to provide an informative and balanced explanation of your topic. Avoid using the first or second person (“I” or “you”).

The structure of your expository essay will vary according to the scope of your assignment and the demands of your topic. It’s worthwhile to plan out your structure before you start, using an essay outline .

A common structure for a short expository essay consists of five paragraphs: An introduction, three body paragraphs, and a conclusion.

Like all essays, an expository essay begins with an introduction . This serves to hook the reader’s interest, briefly introduce your topic, and provide a thesis statement summarizing what you’re going to say about it.

Hover over different parts of the example below to see how a typical introduction works.

In many ways, the invention of the printing press marked the end of the Middle Ages. The medieval period in Europe is often remembered as a time of intellectual and political stagnation. Prior to the Renaissance, the average person had very limited access to books and was unlikely to be literate. The invention of the printing press in the 15th century allowed for much less restricted circulation of information in Europe, paving the way for the Reformation.

The body of your essay is where you cover your topic in depth. It often consists of three paragraphs, but may be more for a longer essay. This is where you present the details of the process, idea or topic you’re explaining.

It’s important to make sure each paragraph covers its own clearly defined topic, introduced with a topic sentence . Different topics (all related to the overall subject matter of the essay) should be presented in a logical order, with clear transitions between paragraphs.

Hover over different parts of the example paragraph below to see how a body paragraph is constructed.

The invention of the printing press in 1440 changed this situation dramatically. Johannes Gutenberg, who had worked as a goldsmith, used his knowledge of metals in the design of the press. He made his type from an alloy of lead, tin, and antimony, whose durability allowed for the reliable production of high-quality books. This new technology allowed texts to be reproduced and disseminated on a much larger scale than was previously possible. The Gutenberg Bible appeared in the 1450s, and a large number of printing presses sprang up across the continent in the following decades. Gutenberg’s invention rapidly transformed cultural production in Europe; among other things, it would lead to the Protestant Reformation.

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The conclusion of an expository essay serves to summarize the topic under discussion. It should not present any new information or evidence, but should instead focus on reinforcing the points made so far. Essentially, your conclusion is there to round off the essay in an engaging way.

Hover over different parts of the example below to see how a conclusion works.

The invention of the printing press was important not only in terms of its immediate cultural and economic effects, but also in terms of its major impact on politics and religion across Europe. In the century following the invention of the printing press, the relatively stationary intellectual atmosphere of the Middle Ages gave way to the social upheavals of the Reformation and the Renaissance. A single technological innovation had contributed to the total reshaping of the continent.

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An expository essay is a broad form that varies in length according to the scope of the assignment.

Expository essays are often assigned as a writing exercise or as part of an exam, in which case a five-paragraph essay of around 800 words may be appropriate.

You’ll usually be given guidelines regarding length; if you’re not sure, ask.

An expository essay is a common assignment in high-school and university composition classes. It might be assigned as coursework, in class, or as part of an exam.

Sometimes you might not be told explicitly to write an expository essay. Look out for prompts containing keywords like “explain” and “define.” An expository essay is usually the right response to these prompts.

An argumentative essay tends to be a longer essay involving independent research, and aims to make an original argument about a topic. Its thesis statement makes a contentious claim that must be supported in an objective, evidence-based way.

An expository essay also aims to be objective, but it doesn’t have to make an original argument. Rather, it aims to explain something (e.g., a process or idea) in a clear, concise way. Expository essays are often shorter assignments and rely less on research.

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Brief review on ebola virus disease and one health approach

Ebola virus disease (EVD) is a severe and highly fatal zoonotic disease caused by viruses in the family Filoviridae and genus Ebolavirus . The disease first appeared in Zaire near the Ebola River in 1976, now in the Democratic Republic of the Congo. Since then, several outbreaks have been reported in different parts of the world, mainly in Africa, leading to the identification of six distinct viral strains that cause disease in humans and other primates. Bats are assumed to be the main reservoir hosts of the virus, and the initial incidence of human epidemics invariably follows exposure to infected forest animals through contact or consumption of bush meat and body fluids of forest animals harboring the disease. Human-to-human transmission occurs when contaminated body fluids, utensils, and equipment come in contact with broken or abraded skin and mucous membranes. EVD is characterized by sudden onset of ‘flu-like’ symptoms (fever, myalgia, chills), vomiting and diarrhea, then disease rapidly evolves into a severe state with a rapid clinical decline which may lead potential hemorrhagic complications and multiple organ failure. Effective EVD prevention, detection, and response necessitate strong coordination across the animal, human, and environmental health sectors, as well as well-defined roles and responsibilities evidencing the significance of one health approach; the natural history, epidemiology, pathogenesis, and diagnostic procedures of the Ebola virus, as well as prevention and control efforts in light of one health approach, are discussed in this article.

1. Introduction

Ebola virus is recognized as an emerging and re-emerging zoonotic disease that causes acute hemorrhagic fever in humans and has a high case fatality rate [ 1 ]. The virus infects humans who come into direct contact with sick animals or people, and most Ebola virus disease(EVD) outbreaks are caused by person-to-person transmission. Several thousand people died because of a recent EVD outbreak in West Africa [ 2 ]. The main outbreaks have been documented in humans, primarily in central Africa [ 3 ] (see Table 1 ).

a chronological list of the major outbreaks of Ebola virus disease in humans.

The Ebola virus was initially identified in 1976 during two unrelated epidemics in southern Sudan and northern Zaire, the Democratic Republic of Congo. The virus was named Ebola virus after the Ebola river. Following laboratory characterization of the viruses recovered during these outbreaks, it was discovered that the viruses from the two outbreaks belonged to the Zaire ebolavirus and Sudan ebolavirus strains and were antigenically, biochemically, and virologically distinct [ 5 ]. A major outbreak of Ebolavirus disease in Western African countries in 2014 spread quickly to several other countries, culminating in an alarming situation worldwide [ 6 ].

The Ebola virus belongs to the family Filoviridae along with the genus Marburgvirus . This family is a member of the order Mononegavirales, which also includes members of Bornaviridae, Paramyxoviridae, and Rhabdoviridae [ 7 ]. Currently, the genus Ebola virus includes six distinct strains: Zaire ebolavirus ( EBOV ), Sudan ebolavirus ( SUDV ), Tai forest ebolavirus ( TAFV ), Bundibugyo ebolavirus ( BDBV ), Bombali ebolavirus ( BOMV ), and Reston ebolavirus ( RESTV ) [ 8 , 9 ]. Among these, EBOV causes Ebola Hemorrhagic Fever (EHF), which has the highest death rate in humans (57%–90%), followed by SUDV (41%–65%), and Bundibugyo ebolavirus (40%). Tai Forest ebolavirus has only been linked to one nonfatal human infection, whereas Reston ebolavirus causes asymptomatic infections in humans [ 10 , 11 ].

Ebola spreads through direct contact with the blood or bodily fluids of a person with a disease [ 12 ]. EVD begins with flu-like symptoms, stomach pain, diarrhea, and/or vomiting, followed by unexplained bleeding or characteristic hemorrhages caused by damaged blood vessels, eventually leading to high mortality [ 13 ]. The current nature of global trade and tourism has increased the chances of Ebola virus spreading to other continents, causing massive outbreaks. The recent epidemics should serve as a wake-up call to the world, ensuring that everyone is well prepared for the next pandemic if one occurs [ 14 ]. One Health Approach is a multidisciplinary approach that promotes collaboration between various sectors, including public, animal, and environmental health, to address the complex health concerns that the world is facing [ 15 ]. Ebola virus are believed to have originated in fruit bats. For instance, the 2007 Ebola virus disease outbreak in Luebo, DRC, originated from the consumption of a freshly killed bat [ 16 ]. Similarly, the 2014 outbreak of Ebola virus disease in West Africa started with a single zoonotic spillover event from fruit bats to a 2-year-old boy in Guinea [ 17 ]. Hence, preventing and controlling EVD require a multifaceted approach that includes surveillance, early detection, rapid response, and effective communication. One Health Approach recognizes that many diseases that affect humans originate in animals and that improving animal health can have a positive impact on human health [ 17 ]. The adoption of the One Health approach has significant implications for communities in developing countries. The health of people, animals, and the environment are interconnected and impact each other, making it important to address health issues holistically [ 18 ]. Therefore, this review highlights the natural history, epidemiology, pathogenesis, diagnostic techniques, and prevention and control strategies of Ebola virus disease in light of one health approach.

2. The History of Ebola outbreaks

The first known Ebola virus outbreak occurred in 1976, with simultaneous Ebola strain outbreaks in Yambuku, northern Zaire (now the Democratic Republic of the Congo, DRC), and Southern Sudan. The Ebola river was named the Zaire ebolavirus [ 19 ]. In 1994, an ethnologist fell ill after examining a dead chimpanzee in Tai National Park on the Ivory Coast [ 5 ]. The virus was distinct from viruses linked to outbreaks in the DRC and Sudan. Thus, it is referred to as Tai Forest ebolavirus [ 9 ]. An outbreak of a mystery disease in Reston, Virginia, USA, in 1990 occurred among cynomolgus crab-eating macaque monkeys that were brought from the Philippines. It was later determined to be an Ebola virus strain of Asian origin and named Reston ebolavirus [ 20 ]. In 2007, a new strain of Ebola virus emerged in Western Uganda in the township of Bundibugyo. This marked the discovery of a fifth strain of the virus, Bundibugyo ebolavirus [ 21 ]. During the years 2013–2015, Western Africa experienced its deadliest Ebola outbreak. The outbreak, which was first reported in Guinea in March 2014 but was eventually traced back to the end of 2013, was the first time an Ebola virus variant had spread across people for such a long time [ 22 , 23 ]. Bombali ebolavirus ( BOMV ) was first discovered in bats in Sierra Leone in 2018; however, it remains unknown whether it causes disease in either animals or people, major cases and outbreaks of Ebola virus disease in human are summarized chronologically (Table, 1) [ 8 ].

3. Ebola virus

Ebola virus vary greatly in size, with diameters ranging from 50 to 80 nm and lengths ranging from 10,000 to 14,000 nm. Virions range in shape, from cylinders to branches and loops. However, all filoviruses retain unique thread-like filamentous structures [ 24 ]. Ebola virus has a large negative-strand, non-segmented RNA of approximately 19 kb. The RNA genome contains seven genes that are sequentially ordered. The genes included 3′ leader-nucleoprotein (NP) –virion protein(VP) 35, matrix protein VP40, glycoprotein(GP), VP30, VP24, and RNA-dependent RNA polymerase (L)-5′ trailer. Except for GP, which encodes three glycoproteins, each gene encodes a single protein product [ 25 ]. The genomes of the six Ebola viruses ( BDBV , EBOV, RESTV , SUDV , BOMV , and TAFV ) differ in sequence, number, and location of gene overlaps [ 8 , 26 ].

4. Epidemiology of EVD

4.1. host and reservoir range.

The precise host and reservoir ranges remain unknown. However, there are indications that the primary hosts of Ebola virus are primates, including humans, chimpanzees, gorillas, and monkeys [ 14 , 25 ]. The natural reservoirs of Ebola virus are thought to be the fruit bats of the Pteropodidae family. Duikers, non-human primates, cats, foxes, hogs, antelopes, porcupines, and rodents are among the animals that are considered potential intermediate or incidental hosts of Ebola virus. However, unlike bats, these animals typically suffer from severe and often fatal illnesses when infected. These animals can carry the virus asymptomatically and shed it in their bodily fluids, which can infect humans who come into contact with it through hunting or handling of bushmeat [ 14 , 27 , 28 ].

Studies have indicated that the virus has the ability to survive in bodily fluids and tissues, such as semen, vaginal fluids, sweat, aqueous humor, urine, and breast milk of individuals who have recovered from the disease [ 29 , 30 ]. A scenario that can result in the recurrence of Ebola virus infection in individuals who had previously recovered from EVD [ 25 ].

4.2. Transmission among humans

The Ebola virus is transmitted to humans by coming into contact with the blood, organs, or other bodily fluids of infected animals. The first case of Ebola virus disease during the 2014–2016 West Africa outbreak was traced to exposure to bats [ 17 ]. Besides bats, EVD cases have been reported in people who handle infected chimpanzees, gorillas, and forest antelopes, whether alive or dead, in Gabon, the Republic of the Congo, and Cote d'Ivoire [ 2 ]. The virus can enter the body through the nose, mouth, eyes, ears, wounds, open wounds, cuts, or mucous membranes [ 31 ]. Transmission through sexual contact with a convalescent or survivor of Ebola virus has been documented [ 32 ]. Ebola virus is present in all bodily fluids of people with EVD, including blood, vomit, urine, feces, sweat, tears, breast milk, semen, mucus, saliva, and other bodily fluids [ 33 ]. Reusing contaminated needles and medical supplies without first sterilizing them can spread the Ebola virus. The virus can survive for weeks on surfaces such as utensils, bedding, clothing, furniture, doorknobs, electrical switches, and other items that can become contaminated by body fluids [ 28 ].

4.3. Pathogenesis

The Ebola virus targets the mononuclear phagocytic system. Entry of Ebola virus through the skin or mucosa paves the way for its entry into target monocytes, macrophages, and dendritic cells. These cells play a pivotal role in viral dissemination [ 13 ]. Ebola viral spike glycoprotein initially mediates viral entry into macrophages and dendritic cells. There is significant evidence that this is a key step in disease [ 34 ]. As a result, the adaptive immune response fails, including the inability to co-stimulate chemokines, up-regulation of the major histocompatibility complex(MHC), and failure to induce lymphocyte differentiation. In addition, interferon synthesis is inhibited [ 35 , 36 ].

Multiple organ dysfunction syndrome (MODS), which results from persistent severe systemic vascular inflammation is observed in the latter stages of EVD, which is characterized by generalized increased capillary permeability, capillary leak, and edema [ 37 ]. Organ dysfunction in MODS is caused by alterations in capillary permeability, changes in blood flow, and the occurrence of microthrombi and microvascular stasis [ 34 ].

4.4. Clinical manifestations

Ebola virus disease (EVD) in humans presents with a range of clinical manifestations. Symptoms typically appear abruptly, with an incubation period of 2–21 days after infection. The initial symptoms of EVD include fever, chills, headaches, body aches, and fatigue. These symptoms are often followed by gastrointestinal symptoms such as nausea, vomiting, diarrhea, and abdominal pain [ 38 ].

As the disease progresses, patients may develop significant weakness with severe exhaustion and dehydration. This may lead to complications, such as hypotension, shock, and multi-organ failure. In severe cases, patients experience profuse external and internal bleeding, a hallmark of EVD, a condition termed Ebola hemorrhagic fever. Additionally, EVD can cause neurological symptoms such as confusion, seizures, and coma [ 9 ]. Symptoms may vary depending on the individual, and some patients may not manifest all the symptoms. However, those who develop symptoms are highly contagious during the acute phase of the disease, making early detection and isolation of cases crucial for preventing the spread of the virus [ 6 ].

5. Diagnosis of EVD

5.1. definitive diagnosis.

The most commonly used diagnostic tests for EVD include reverse transcription polymerase chain reaction (RT-PCR) and antigen-capture enzyme-linked immunosorbent assay (ELISA). These tests detect Ebola virus genetic material or protein in the blood or other body fluids. RT-PCR is highly sensitive and can detect viruses even in the early stages of infection. ELISA is less sensitive but can detect antibodies produced by the immune system against the virus [ 39 ]. Currently, WHO recommends automated or semi-automated nucleic acid testing (NAT) for regular diagnostic management and rapid antigen detection assays for use in distant locations [ 40 ]. Antibody detection does not play a role in the diagnosis of acute EVD but may be useful in epidemiological and surveillance studies. A negative test result within 48 h of exposure to Ebola virus does not exclude infection [ 41 ].

5.2. Differential diagnosis

EVD can show symptoms similar to those of other infectious diseases; therefore, a differential diagnosis is essential to eliminate other illnesses with similar clinical symptoms. Diseases that might be considered as differential diagnoses for EVD include malaria, Lassa fever, dengue fever, yellow fever, typhoid fever, cholera, influenza, SARS, and MERS [ 42 ]. It is necessary to consider the possibility of EVD in anyone who has traveled to or resided in regions where EVD outbreaks have occurred or who has had close contact with a confirmed EVD case [ 6 , 43 ]. In tropical regions, where various febrile diseases can mimic the symptoms of EVD, immediate diagnosis should be made [ 44 ].

6. Treatement of EVD

Currently, two drugs are approved by the U.S. Food and Drug Administration (FDA) to treat EVD caused by Zaire ebolavirus. The first approved drug is Inmazeb (atoltivimab, maftivimab, and odesivimab), a combination of three monoclonal antibodies has been the first FDA-approved treatment for Zaire ebolavirus infection in adult and pediatric patients. Inmazeb targets glycoproteins on the surface of the Ebola virus which aids host cell entry. Inmazeb's three antibodies can bind to this glycoprotein simultaneously, preventing viral attachment and entry [ 45 ]. The second approved drug for use in Zaire ebolavirus infection in adults and children is ansuvimab (mAb114), a human monoclonal antibody, to be treated for Zaire ebolavirus infection in adults and children. Ansuvimab blocks the binding of the virus to cell receptors, preventing viral entry into the cell [ 46 ]. Overall survival was significantly greater in individuals who received either of the two FDA-approved therapies [ 45 ].

Furthermore, to maintain optimal organ function, patients need personalized supportive treatment based on their problems [ 47 ]. Rehydration with oral or intravenous fluids, as well as the treatment of particular symptoms, increases survival. Analgesics are indicated to reduce pain, whereas intravenous fluids are recommended to maintain osmotic balance. Critically ill patients may require intensive care and support [ 13 ].

6.1. Vaccination

Vaccine development has started in the past decades, concurrent with the introduction of the Ebola virus into the human population. However, the first Ebola virus vaccine, Ervebo, a vesicular stomatitis virus-based vaccine, was only recently approved and has proven successful in protecting people against the Zaire ebolavirus strain. Ervebo is a live, attenuated vaccine that has been genetically modified to incorporate a protein from the Zaire ebolavirus . It was administered as a single dose. The most commonly reported side effects are pain, edema, and redness at the injection site, as well as headache, fever, joint and muscle aches, and fatigue [ 48 ].

The second officially approved vaccine for EVD is a two-dose regimen vaccine named Zabdeno and Mvabea for people aged 1 year and older. The vaccine was administered in two doses: Zabdeno was administered initially, followed by Mvabea, approximately 8 weeks later. As a result, this prophylactic 2-dose regimen is not appropriate for an epidemic response where immediate protection is required [ 49 ]. Despite ongoing efforts to develop new vaccines such as SUDV , only two vaccines have been authorized for human use [ 1 ].

7. Prevention and control

Controlling epidemics necessitates the coordination of medical services, which includes early detection, contact tracing for persons who have been exposed to, treatment for people who have been exposed to Ebola virus, and vaccination of frontline health workers and at-risk individuals [ 50 ]. In some countries affected by Ebola virus, multi-level and multi-sectoral approaches have been implemented to prevent the spread of the disease. These measures were not limited to health services and other sectors of society, and all levels of government were involved. A holistic approach enabled countries to enhance their preparedness to combat the outbreak from multiple perspectives and to tackle the different elements that contributed to its expansion [ 51 ].

Studying and learning from the successful strategies used during these outbreaks could prove valuable in preparing for future outbreaks and improving our ability to contain them. By adopting a similar multilevel and multisectoral approach, we may be able to generate a more effective response and reduce the impact of future Ebola outbreaks [ 52 ]. Public education about this deadly disease is also critical for preventing its spread [ 53 ]. Proper monitoring of airports and public places where there is a high risk of infection spread is critical [ 54 ]. Patients who become ill should be monitored for at least 21 days to rule out infections. All protective clothing, such as gowns, gloves, face masks, goggles, and respirators, should be worn by healthcare workers and practice nursing barriers. Samples collected for diagnosis should be transported with extreme caution and handled only at Biosafety Containment Level 4 [ 14 ]. Because bush meat has been identified as a potential and significant source of epidemics in the past, it is critical to monitor its consumption and illegal export to developing countries [ 55 ] . Safe sex practice for recovered individuals and utilization of currently approved vaccines for frontline workers and at-risk individuals is a recommended prevention practice [ 1 ].

8. One health approach

The One Health (OH) programme is a collaborative approach that aims to maintain the well-being of humans, animals, and the environment. Since ancient times, animal studies have influenced human medicine. In the past, the fields of human and animal medicine were closely linked; however, owing to the emphasis on specialization during the Industrial Revolution, the connection between these fields gradually decreased in the early 20th century [ 56 ]. In the last three decades, it has become clear that most new and emerging infections that can be transmitted from animals to humans have their origins in animals, particularly in wild animals. It is apparent that human activities such as changes in land use, intensification of ecosystems, urbanization, international travel, and trade are the primary causes of their emergence [ 57 ]. Studies indicate a correlation between recent deforestation incidents and a greater likelihood of an EVD outbreak occurring in a particular area [ 58 ]. To obtain knowledge about each newly emerging zoonotic disease and formulate a plan to respond and control it, a collaborative, interdisciplinary approach that entails animal, human, and environmental health is needed to comprehend the ecology of each disease and carry out risk assessment [ 59 ].

The One Health approach emphasizes the impacts, reactions, and measures taken at the interfaces between animals, humans, and ecosystems. This approach is particularly relevant for addressing emerging and endemic zoonoses, with the latter being responsible for a significantly greater disease burden in developing countries and having a significant social impact in areas with limited resources [ 60 ]. Zoonosis accounts for up to 60% of emerging infectious diseases reported globally. Understanding the complex interdependence of humans, animals, and the environment is important for the design and implementation of effective interventions for EVD outbreak response [ 43 ]. The global economy has enabled rapid movement of people, animals, plants, and agricultural goods worldwide. This has contributed to more frequent outbreaks of zoonotic infections in impoverished populations. Improved coordination across sectors is required to match responses to the current disease ecology [ 61 ]. The epidemic response highlights the importance of strong institutional collaborations as well as efficient and effective communication methods, diagnostic tools, and disease prevention strategies [ 62 ].

Establishing a prioritized list of zoonotic diseases and committing to sharing resources between participants from various fields, such as humans, animals (domestic and wildlife), and environmental health, simplifies the establishment of multisectoral collaborations [ 63 ]. The early involvement of several sectors fosters teamwork and guarantees program ownership [ 64 ]. One health approach involves properly measuring the burden of zoonotic diseases, which is a crucial step in setting public and animal health priorities and evaluating the success of prophylactic and control strategies [ 61 ]. Effective zoonotic disease prevention, detection, and response necessitate strong coordination across the animal, human, and environmental health sectors, as well as well-defined roles and responsibilities. Countries can consider holding frequent cross-sectoral meetings to foster cross-sectoral and multidisciplinary collaboration, promote transparency, and coordinate activities across agencies. Developing mutually agreed-upon standard operating procedures is critical and can be achieved by establishing a One Health coordination unit and conducting collaborative outbreak investigations and response operations [ 56 , 63 , 64 ]. Ebola virus is a zoonotic pathogen that can transfer between animals and humans, highlighting the need for a comprehensive One Health approach to understand and manage the transmission of the virus [ 15 , 43 ].

One Health methodology acknowledges the interdependent nature of human, animal, and environmental health, emphasizing the inefficacy of a disjointed approach in combatting diseases, such as Ebola. For instance, the Ebola outbreak in West Africa between 2014 and 2016 was primarily due to increased interactions between humans and wildlife as a result of farming and deforestation [ 22 , 43 ].

Adopting the One Health approach enables researchers and public health officials to better comprehend the ecology of the Ebola virus and how it can be transferred between various species. In addition, with effective coordination, the One Health approach can identify and address the underlying factors that may contribute to the emergence of viruses and transmission, and develop targeted intervention strategies to contain its spread [ 43 ]. Overall, the One Health approach is an invaluable tool for addressing emerging diseases such as Ebola, providing the potential to prevent further outbreaks [ 15 ].

9. Conclusion and recommendation

EVD has been known since 1976, but its severity, exceptionally infectious or contagious nature, and acquisition of pandemic status in 2014–2015 have raised numerous concerns among health professionals and policymakers. The emergence of Ebola as a threat has warned us to prepare arsenals for combating Ebola-like diseases through multidisciplinary and collaborative approaches that transcend national boundaries. This is the right time to address the EVD emergency by developing and deploying cutting-edge tools and techniques for confirmatory diagnosis, as well as developing internationally compatible surveillance, monitoring, and networking systems, and identifying animal reservoirs. Effective Ebola virus disease prevention, detection, and control necessitate strong coordination across animal, human, and environmental health sectors, as well as well-defined roles and responsibilities. The WHO is urging public health authorities to remain alert and ready to respond to emergencies. Furthermore, strong surveillance and immediate response capacity need to be upheld, and care, screening, and counseling also need to be provided to survivors. Further research to study and completely comprehend the geographic extent and reservoir species involvement is critical for assessing the risk of future outbreaks.

Funding information

This review did not receive any specific grants from funding institutions in the public, commercial, or not-for-profit sectors.

Ethics statement

The author states that the review meets all the necessary ethical guidelines, including conforming to the legal requirements of the review writing.

Author contribution

Hassan Abdi Hussein: conceived and designed the article, extracted the data, Wrote the article and critically revised its important intellectual content; and finally approved the submitted version.

Declaration of competing interest

The authors declare that they have no known competing financial interests or personal relationships that could have appeared to influence the work reported in this paper.

Acknowledgements

Author would like to take this opportunity, to express a heartfelt thanks to Dr Yonas Gizaw for providing critical comments and useful input information to work on this review topic.

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Ebola virus disease

• Vaccines to protect against some types of Ebola have been used to control the spread of Ebola in outbreaks. Other vaccines are in development.
• Early supportive care with rehydration and the treatment of symptoms improves survival.
• WHO has made strong recommendations for the use of two monoclonal antibody treatments in treating Ebola: mAb114 (Ansuvimab; Ebanga) and REGN-EB3 (Inmazeb).
• The average Ebola case fatality rate is around 50%. Case fatality rates have varied from 25–90% in past outbreaks, depending on circumstances and the response.
• Good outbreak control relies on taking many types of actions: care of patients, infection prevention and control, disease surveillance and contact tracing, good laboratory services, safe and dignified burials, and social mobilization.
• Community engagement is key to successfully controlling outbreaks.

Ebola virus disease (EVD or Ebola) is a rare but severe illness in humans. It is often fatal.

People get infected with Ebola by touching:

• infected animals when preparing, cooking or eating them
• body fluids of an infected person such as saliva, urine, faeces or semen
• things that have the body fluids of an infected person like clothes or sheets.

Ebola enters the body through cuts in the skin or when touching one’s eyes, nose or mouth.

Early symptoms include fever, fatigue and headache.

Some types of Ebola can be prevented with vaccines and treated with medicines.

Ebola first appeared in 1976 in 2 simultaneous outbreaks, one in what is now Nzara, South Sudan, and the other in Yambuku, Democratic Republic of the Congo. The latter occurred in a village near the Ebola River, from which the disease takes its name.

The virus family Filoviridae includes 3 genera: Cuevavirus, Marburgvirus, and Ebolavirus. Within the genus Ebolavirus, 6 species have been identified: Zaire, Bundibugyo, Sudan, Taï Forest, Reston and Bombali.

Transmission

It is thought that fruit bats of the Pteropodidae family are natural Ebola virus hosts. Ebola is introduced into the human population through close contact with the blood, secretions, organs or other bodily fluids of infected animals such as fruit bats, chimpanzees, gorillas, monkeys, forest antelope or porcupines found ill or dead or in the rainforest.

Ebola then spreads through human-to-human transmission via direct contact (through broken skin or mucous membranes) with:

• blood or body fluids of a person who is sick with or has died from Ebola; and
• objects that have been contaminated with body fluids (like blood, feces, vomit) from a person sick with Ebola or the body of a person who died from Ebola.

Health-care workers have frequently been infected while treating patients with suspected or confirmed Ebola. This occurs through close contact with patients when infection control precautions are not strictly practiced.

Burial ceremonies that involve direct contact with the body of the deceased can also contribute to the transmission of Ebola.

People remain infectious as long as their blood contains the virus. After recovery, there is the possibility of sexual transmission, which can be reduced with support and information for survivors .

Pregnant women who get acute Ebola and recover from the disease may still carry the virus in breastmilk, or in pregnancy related fluids and tissues.

For more, read the guidelines on the management of pregnancy and breastfeeding in Ebola.

The symptoms of Ebola infection can be sudden and include fever, fatigue, muscle pain, headache and sore throat. These are followed by vomiting, diarrhoea, rash, and internal and external bleeding.

The time from when someone gets infected to having symptoms is usually from 2 to 21 days. A person with Ebola can only spread the disease once they have symptoms. People can spread Ebola for as long as their body contains the virus, even after they have died.

After recovering from Ebola, some people may have symptoms for two years or longer. These symptoms can include:

• feeling tired
• muscle and joint pain
• eye pain and vision problems
• weight gain
• belly pain and loss of appetite
• hair loss and skin problems
• trouble sleeping
• memory loss
• hearing loss
• depression and anxiety.

People should speak to a health-care professional if they have:

• symptoms and have been in an area known to have Ebola, or
• been in contact with someone who may have had Ebola.

It can be difficult to clinically distinguish Ebola virus disease from other infectious diseases such as malaria, typhoid fever and meningitis. Many symptoms of pregnancy and Ebola disease are also quite similar. Because of risks to the pregnancy and themselves, pregnant women should ideally be tested rapidly if Ebola is suspected.

Confirmation that symptoms are caused by Ebola virus infection are made using the following diagnostic methods:

• antibody-capture enzyme-linked immunosorbent assay (ELISA)
• antigen-capture detection tests
• serum neutralization test
• reverse transcriptase polymerase chain reaction (RT-PCR) assay
• electron microscopy
• virus isolation by cell culture.

Diagnostic tests evaluated through the WHO emergency use assessment and listing process can be seen here.

People with symptoms of Ebola should get medical care immediately. Early care improves a person's chances of surviving Ebola.

Treatment includes oral or intravenous fluids and medicines provided in the hospital.

It is not safe to care for people with Ebola at home, because the person may make other people sick. At home, they will not receive the same level of care they can get from professionals.

There is an effective vaccine for the Zaire type of Ebola, which is mostly found in Guinea and the Democratic Republic of the Congo. It is treated with antibodies. These antibody medicines are given intravenously and increase the chances of survival.

Research is ongoing to find vaccines and treatments for other types of Ebola.

For all types of Ebola, supportive treatments save lives and include the following:

• oral or intravenous fluids
• blood transfusions
• medicines for other infections the person may have, such as malaria
• medicines for pain, nausea, vomiting and diarrhoea.

WHO has guidance that outlines the optimized supportive care Ebola patients should receive, from the relevant tests to administer, to managing pain, nutrition and co-infections (such as malaria), and other approaches that put the patient on the best path to recovery.

In the 2018–2020 Ebola outbreak in the Democratic Republic of the Congo, the  first-ever multi-drug randomized control trial  was conducted to evaluate the effectiveness and safety of drugs used in the treatment of Ebola patients. WHO has living guidance on the recommended treatments and approaches.

More information on Ebola clinical management

Prevention and control

People can protect themselves from getting Ebola by:

• washing hands
• avoiding touching the body fluids of people who have, or may have, Ebola
• not touching the bodies of people who have died from Ebola
• getting the Ebola vaccine if they are at risk for the Zaire type of Ebola.

The Ervebo vaccine has been shown to be effective in protecting people from the species Zaire ebolavirus and is recommended by the Strategic Advisory Group of Experts on Immunization as part of a broader set of Ebola outbreak response tools.

WHO prequalifies Ebola vaccine, paving the way for its use in high-risk countries

Good outbreak control relies on applying a package of interventions, including case management, surveillance and contact tracing, a good laboratory service, safe burials and social mobilisation. Community engagement is key to successfully controlling outbreaks. Raising awareness of risk factors for Ebola infection and protective measures (including vaccination) that individuals can take is an effective way to reduce human transmission. Risk reduction messaging should focus on several factors:

• reducing the risk of wildlife-to-human transmission
• reducing the risk of human-to-human transmission
• outbreak containment measures, including safe and dignified burial of the dead
• reducing the risk of possible sexual transmission
• reducing the risk of transmission from pregnancy related fluids and tissue.

Health-care workers should always take standard precautions when caring for patients, regardless of their presumed diagnosis. These include basic hand hygiene, respiratory hygiene, use of personal protective equipment (to block splashes or other contact with infected materials), safe injection practices and safe burial practices.

Health-care workers caring for patients with suspected or confirmed Ebola virus should apply extra infection control measures to prevent contact with the patient’s blood and body fluids and contaminated surfaces or materials such as clothing and bedding.

Laboratory workers are also at risk. Samples taken from humans and animals for investigation of Ebola infection should be handled by trained staff and processed in suitably equipped laboratories.

WHO has developed detailed advice on Ebola infection prevention and control:

• Infection prevention and control guidance for care of patients with suspected or confirmed Filovirus haemorrhagic fever in health-care settings, with focus on Ebola

WHO response

WHO works with countries to prevent Ebola outbreaks by maintaining surveillance for Ebola virus disease and supporting at-risk countries to develop preparedness plans. This document provides overall guidance for control of Ebola and Marburg virus outbreaks:

• Ebola and Marburg virus disease epidemics: preparedness, alert, control, and evaluation

When an outbreak is detected, WHO responds by supporting community engagement, disease detection, contact tracing, vaccination, case management, laboratory services, infection control, logistics, and training and assistance with safe and dignified burial practices.

WHO has a range of advice and guidance for managing Ebola outbreaks:

• Clinical management
• Disease outbreaks
• Health product policy and standards - vaccine standardization
• Medical devices for Ebola outbreak
• Sexual and Reproductive Health and Research (SRH) and Ebola
• FAQs on Ebola virus disease
• FAQs on Ebola vaccines
• Ebola virus disease outbreak, Guinea: Multi-country strategic readiness and response plan
• Health Care Readiness: Ebola clinical management
• Clinical care for survivors of Ebola virus disease
• Therapeutics for Ebola virus disease
• Publications on Ebola virus disease 
• Ebola outbreak 2022 - Équateur Province, DRC

Ebola Virus Epidemic

How it works

In 2014, the world was horrified when an unknown outbreak occurred and caused a major epidemic worldwide. The world was terrified especially when the outbreak occurred in Guinea and traveled West to the United States and many other countries without knowing what kind of disease that was killing people and infecting our healthcare workers. The virus was later known to be a Zaire Ebolavirus outbreak declared by the World Health Organization (CDC). The Ebola virus is a rare but deadly disease. As the number begins to rise within month in the United States, the Center of Disease Control (CDC) responded to the outbreak by screening everyone at the airport who has traveled from West Africa to help identify those who are at risk.

In addition, the CDC also trained healthcare workers on infection prevention and control practices since the last time the Zaire virus occurred was decades ago and healthcare workers are the ones working closely with the infected patients.

• 1 Disease Description
• 2 History of Disease
• 3 Reason for Emergence
• 4 Methods of Prevention
• 5 Conclusion

Disease Description

The Ebola virus is a native disease to Africa known to be a part of the Filoviridae family causing severe hemorrhage fever which is an unknown bleeding throughout parts of the body, but mostly in the eyes, ears, and etc. and eventually death. According to Center of Disease Control (CDC), when humans are infected with the Ebola virus, symptoms may appear within 2 to 21 days of coming into contact with the virus. However, people who are exposed to the virus are not infected until symptoms appear. The symptoms are similar to a flu such as a fever, severe headaches, fatigue, weakness, muscle and abdominal pain, vomiting, diarrhea, and unexplained bleeding (CDC). Additionally, the virus was first introduced to the human population by direct contact with blood, secretion, organs, feces, and bodily fluid of an infected animal found dead or ill in the rainforest (WHO). In the past, health care workers have been mostly infected by the disease by treating patients suspected or confirmed to have the Ebola virus without the knowledge of the disease as it occurred decade ago. Lastly, volunteers and healthcare workers were infected by coming into direct contact with the decease remains at the burial site without using the proper gear.

History of Disease

The Ebola virus was first discovered in 1976, in two separate places in West Africa due to outbreaks that occurred in Nzara, South Sudan about 500 miles away from the Ebola River known as the Sudan Ebolavirus and a hospital in the Yambuku, Democratic Republic of Congo a village near the Ebola River which gave the name of the disease as the Ebola strain ran along the river (CDC). The disease found in the Democratic Republic of Congo was later known as the Zaire Ebolavirus and the disease found in South Sudan was later known as the Sudan Ebolavirus and resulted in a high fatality rate (53%-90%). Since the first discovery, scientists have discovered five strains of the Ebola virus; however, only four of the strains can transmit the disease to humans and one of the strains can only be found in animals. The four types of strains that are known to be found in human by direct contact from human to human transmission or animal to human transmission are: Zaire, Sudan, Tai Forest (Cote d’lvoire), and Bundibugyo. Lastly, the only type of strain not found in human, but can only found in animals from the host is Reston.

In 1994, the Cote d’Ivoire Ebolavirus was discovered in the Tai Forest, which involved the first single non-fatal case from a veterinarian, whom was performing an autopsy on the infected Chimpanzee (Towner, J. S., Sealy, T. K., Khristova, M. L., & et al., 2008). In addition, Bundibugyo Ebolavirus was later found in 2007. Bundibugyo is distantly related to Cote d’Ivoire resulting in 29 suspected and 56 confirmed cases with the lowest mortality rate. Leading Zaire, Sudan, and Bundibugyo to be the only three species to have the largest Ebola outbreaks in Africa ranging from 25% to 90% (Coltart, C. E. M., Lindsey, B., Ghinai, I., & et. al., 2017). Furthermore, it has been said that the African fruit bats are the reservoir host; and scientist have found these bats to carry antibodies and viral RNA fragments, but are unable to isolate the virus itself to see how the bats are able to host the virus (KupferschmidtJun, K., NormileJul, D., & et al., 2017).

Reason for Emergence

Since the first Zaire Ebolavirus occurred in 1976, confirming 318 cases and 280 deaths, the CDC understood the disease and how to prevent it from spreading. The reason for the reemergence was reported on December 2013, when an 18-month-old boy from a small village in Guinea was believed to be infected by a fruit bat and five more cases occurred with symptoms of fatal diarrhea (CDC). It was not until March 13, 2014 when the Ministry of Health in Guinea reported an alert of an unknown illness killing people rapidly, fever, severe diarrhea, and vomiting, which was later identified through epidemiology investigation and blood sample by the Pasteur Institute in France that the unknown illness killing people rapidly was the Zaire Ebolavirus. On March 23, 2014, it was reported that there were 49 confirmed cases and 29 death (CDC). The Zaire Ebolavirus was poorly contained, allowing the virus to spread to nearby countries like Liberia and Sierra Leone due to a weak surveillance system and poor infrastructure of the public health where cases were slowly noticed and identified. Yet, some cases remain unreported. Hence, the reason to why the Ebola virus cases kept on reappearing. About two and a half year later, there have been 28,600 cases and 11,325 deaths (CDC). In Liberia, the Ebola virus took 8% of the doctors, nurses and midwives’ lives; however, about 30,000 children became orphans after the 2014- 2016 Ebola epidemic and about 20% of all the Ebola cases occurred in children ages 15 and under (CDC).

Meanwhile, in the United States, on September 30, 2014, the first confirmed case occurred in Dallas, Texas where the patient traveled from West Africa to Dallas. Later, the first confirmed patient died, but the healthcare workers who were treating the patient was confirmed with the Ebola virus and recovered. This showed a downfall in the healthcare system because the healthcare workers handled the Ebola infection poorly allowing transmission of the infection to spread affecting and increasing the death among healthcare workers. In total, there have been a total of 11 patients treated with the Ebola virus in the United States, and 4 of the patients’ symptoms occurred after arriving in the United States from West Africa.

Methods of Prevention

The 2014 2016 Ebola epidemic took a total of 28,652 suspected cases, 15,261 confirmed cases, and 11,325 deaths worldwide (CDC). The CDC responded to the outbreak after seeing how poorly the surveillance was handled by allowing the disease to spread quickly to nearby countries and worldwide before identifying the virus. In addition, with monitoring the rise in the number of cases confirmed was not completely accurate as there were still Ebola cases that were unreported and lost due to no free access to medical (Coltart, C. E. M., Lindsey, B., Ghinai, I., & et. al., 2017). As the cases in the United States occurred from people traveling to West Africa and becoming infected after arriving in the United States, the CDC started to conduct a screening at the airport of those traveling from West Africa as the first two cases occurred from patients traveling from West Africa. In addition, the CDC decided to train 55 hospital in 17 states in the United States to get the healthcare workers ready to treat and be on the lookout for any patients with signs or symptoms of the Ebola virus after the healthcare workers who were treating the infected patients were tested positive of have the Ebola virus incidents. Thus, one of the ways to prevent the spread of the Ebola virus is by avoiding going to infected areas of known outbreaks. By doing so, research the place you are traveling to and see if there have been any recent outbreaks before going. If there is an outbreak try to wash your hands frequently and avoid buying and eating wild animals or unknown meat. Also, try to avoid coming into contact with an infected person, by looking up the symptoms of the disease so you know what to notice. Lastly, do not handle any remains of an infected person without the proper personal equipment or allow an expert to handle the body of the decease (Mayo Clinic).

After the 2014 2016 Ebola virus epidemic, the world has a better knowledge and understanding on how to look and treat the disease that once occurred in 1976 that was caused by a nosocomial transmission. As better training was done to conduct a quicker response to the Ebola outbreak will allow future healthcare worker, identify and treat the virus in a timely manner where the disease do not spread to nearby countries within a short amount of time. The public is now aware of where and how the disease originated from and should educate themselves when traveling to the source where an outbreak occurs.

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Ebola - Free Essay Examples and Topic Ideas

Ebola virus disease (EVD), formerly known as Ebola hemorrhagic fever, is a severe and often fatal hemorrhagic disease caused by the Ebola virus, an RNA virus in the family Filoviridae. Symptoms are characterized by high fever, gastrointestinal symptoms (e.g., vomiting, diarrhea, abdominal pain), and unexplained hemorrhage. Ebola gained mainstream coverage when in 2014 when there was an outbreak of EVD in West Africa. This was a global spectacle and of unparalleled scale primarily affecting the countries of Guinea, Liberia, and Sierra Leone. One of the qualities that makes EVD of high public concern is its potential for extremely high mortality rates (up to 90%) (Bodine, Cook, & Shorten, 2018).

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The pathogenesis of Ebola is not clear but, once in the human body, the virus replicates in a variety of cell types—including dendritic cells, monocytes, and macrophages—with consequences including coagulation abnormalities, vascular instability, a robust inflammatory response, and extensive focal necrosis that tends to be most severe in the liver, spleen, lymph nodes, kidney, lung, and gonads. Death typically occurs secondary to a septic shock-like syndrome within 10 days of symptom onset; patients who survive ≥ 2 weeks often recover. The incubation period varies from 2–21 days (but is typically 8–10 days), during which time the infected patient is not contagious; the patient is not considered contagious until the onset of symptoms (typically, fever). Early symptoms are nonspecific and can be confused with those of other diseases, including malaria, dengue, and typhoid fever.

Pathophysiological Process and Clinical Manifestations

The Ebola virus is an enveloped single-stranded negative sense RNA virus member of the family Filoviridae, genus Ebolavirus, and order Mononegavirales. Five Ebola strains have been identified: Zaire Ebolavirus, Bundibugyo Ebolavirus, Taï Forest Ebolavirus, Sudan Ebolavirus, and Reston Ebolavirus (Borchardt, 2015). The current outbreak is most closely related to the Zaire strain, at about 97% homology. The Zaire strain has the highest reported overall mortality, 60% to 88% for previous outbreaks; mortality from the current epidemic strain is estimated at 60% (Borchardt, 2015). The current virus strain likely diverged from a common central African Ebola virus ancestor about 2004, and probably arose from a single natural reservoir transmission, followed by human-to-human transmission with the outbreak.7 The natural reservoir has not been clearly established, but fruit bats from regions of previous Ebola outbreaks have tested positive for Ebola virus, suggesting zoonotic transmission from a bat reservoir.8 The initial human infection is thought to have occurred following contact with an Ebola virus-infected animal, perhaps through the ingestion of contaminated nonhuman primate bush meat or from direct exposure to infected animal blood or fluids (Borchardt, 2015).

Human-to-human transmission occurs through direct exposure to an infected individual’s body fluids, including blood, urine, feces, saliva, vomit, or from objects contaminated with infected fluids (such as needles and syringes). Patients most at risk for contracting Ebola are those from active endemic areas; those who have traveled to these areas within the last 21 days; and those who have had direct percutaneous (needlestick) or mucous membrane exposure to Ebola-infected blood or body fluids, direct skin contact with infected blood or fluids, or direct contact with a dead body without wearing appropriate personal protective equipment (Borchardt, 2015). High-risk patients include family members and friends who may have come in contact with infected fluids of symptomatic patients and healthcare workers directly exposed to infected blood or body fluids because they were not wearing appropriate personal protective equipment or practicing standard biosafety precautions (Borchardt, 2015).

In the initial disease presentation, symptoms of acute-onset fever (temperature greater than 38.6° C [101.5° F]), chills, myalgia, and malaise can be mistaken for other tropical diseases, such as malaria or dengue fever. Ebola can progress to flu-like symptoms with cough, runny nose, and shortness of breath; however, the disease is not airborne. The more prominent symptoms are of a progressive gastrointestinal nature: nausea, vomiting, diarrhea, and abdominal pain that result in intravascular volume depletion, hypoperfusion, shock, profound electrolyte abnormalities, metabolic acidosis, and marked hepatocellular injury with aminotransaminase elevation. Other laboratory findings include anemia, leukopenia, thrombocytopenia, and elevated prothrombin and partial thromboplastin times. Lymphopenia is a marker of poor prognosis.

Ebola testing to confirm diagnosis is only effective after the viral load has reached a level to where symptoms are present. Although the viral load may not be detectable until the patient has been symptomatic for several days, laboratory tests (white blood cell count, liver function, amylase, and coagulation studies) associated with affected organs may show changes (Richardson, 2015). Therefore, supportive treatment of symptoms usually starts before confirmation of the disease.

No vaccine has been proven to prevent Ebola and no antiviral medicine effectively treats the disease. Treatment is limited to basic symptomatic control, administering IV fluids and electrolyte replacement, maintaining oxygen saturation and BP, and treating complicating infections as they arise. A patient’s immune status determines ability to recover from Ebola. Patients who recover develop neutralizing antibodies to Ebola virus that are detectable for up to 10 years, suggesting a potential treatment role for passive immunity. The WHO has approved the use of serum from convalescing patients to treat new patients with acute Ebola. This decision came after the WHO heard testimony about a 1995 Ebola outbreak during which blood products from five convalescing patients were used to treat eight infected patients, and only one patient died.

In time when worldwide travel is more acceptable thanks in part to technological advancements that have permitted healthcare workers to travel to distant lands and assist in providing state of-the-art care to those who are impoverished. As healthcare personnel educate many who are not up to date on basic lifesaving measures, they simultaneously become more susceptible to foreign pathogens such as Ebola Virus Disease.

Ebola Virus Disease (EVD) is a rare and deadly disease in people and nonhuman primates. The viruses that cause EVD are located in sub-Saharan Africa. People can get EVD through direct contact with an infected animal (bat or nonhuman primate) or a sick or dead person infected with Ebola virus (Center of Disease and Control and Prevention [CDC], 2018). The Ebola outbreak is far from over, so PAs, especially first responders in emergency or urgent care facilities, must remain vigilant and informed of the ongoing developments of this epidemic. (Borchardt, 2015).

• Bodine, E.N., Cook, C., & Shorten, M. (2018). The potential impact of a prophylactic vaccine for Ebola in Sierra Leone. Mathematical Biosciences And Engineering: MBE, 15(2), 337-359. https://doi-org.chamberlainuniversity.idm.oclc.org/10.3934/mbe.2018015
• Borchardt, R. (2015). The Ebola virus epidemic: Preparation, not panic. Journal of the American Academy of Physician Assistants, 28(2), 48-50. doi:10.1097/01.JAA.0000459821.32532.10
• Richardson, K. (2015). Ebola virus disease. Advanced Emergency Nursing Journal, 37(2), 102-115. doi:10.1097/TME.0000000000000063

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Home — Essay Samples — Nursing & Health — Ebola Virus — Review on African virus Ebola

Review on African Virus Ebola

• Categories: Ebola Virus Infectious Disease

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Words: 1477 |

Published: Jan 4, 2019

Words: 1477 | Pages: 3 | 8 min read

About Ebola

• Population density
• Contact with contaminated Fluid
• Preparing burial of people who died of Ebola Factors causing mortality:
• Temperature
• Healthcare facilities for symptoms

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