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Protecting Wild African Apes from Ebola

Categories: AfricaEbola

Introduction

Ebola virus has caused more than 20 human outbreaks throughout Africa. One big epidemic in West Africa lasted for more than 2 years from 2013, killing more than 11000 lives [2]. Ebola is not only a major threat to humans, but also to African great apes who are now classified as critically endangered by the International Union for Conservation of Nature [2]. Through laboratory and epidemiological testing, evidence has shown a clear link between human Ebola outbreaks and Ebola-infected apes. This is a result of the contact of humans with infected apes and through the consumption of ape meat.

All eight human outbreaks in the Republic of Congo (ROC) and Gabon that have occurred in the last 25 years were said to be a result of this transmission [2]. This means that the scavenging or hunting of wild great apes is a major risk factor leading to the spread of the Ebola virus [2]. Health organisations seek to regulate the human-animal-environment interactions to reduce the emergence and spread of this infectious disease.

But not only should we avoid predictable chains of Ebola virus transmission, but we should also be preventing Ebola in wild apes to avoid the chance of endangerment and extinction in the future [1].

DiscussionResearchers need to immediately assess what we know about Ebola and think of ways to approach this to prevent Ebola spreading or reoccurring. A good first step would be to develop an Ebola resistant vaccine for humans [1]. This, however, is not easy because it can take up to 14 years to require the evidence needed to prove its effectiveness and safety.

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Furthermore, in the absence of an Ebola outbreak, clinical efficacy in humans cannot be trialled [1]. Trials will always face harsh philosophical, ethical and practical challenges to access these new medicines [1]. A vaccines safety and effectiveness could be tested on the apes before human trial as an approach to provide evidence of a successful vaccine. This is a great way to employ a One Health approach, providing evidence from various species and sources [1]. As a result, this would reduce Ebola transmission between interspecies, protect apes, and accelerate the development of vaccines and licensing for humans [1]. This strategy would, therefore, be beneficial for both humans and apes.

Ethical challenges of separating uninfected apes from the infected apes

Peter Walsh believes that the spread of Ebola through humans has arisen mainly from eating apes and that over the last decade, that they are all part of one large epidemic spreading primarily from ape to ape in Gabon and Congo [5]. Walsh believes that the idea of separating the infected from the uninfected could help protect the apes from being exposed and that there are people out there willing to donate to the project. Conrad Aveling of the European Union conservation organisation ECOFAC in Libreville, Gabon says this is a huge task and has many risks involved [5]. Aveling says it an endless job having to clear 100 kilometres of rivers for tourist in Odzala National Park and that transporting apes to uninfected areas may end up killing more apes than it saves [5]. Les Real, a disease ecologist at Emory University in Atlanta also amplifies risks of separating the apes. Real says other carriers like bats and rodents, who travel long distances, may then spread the Ebola to the uninfected apes and that these huge measures would have just been in futile [5]. It has become an argument between conservationists, disease experts, and primatologists about what should be done to limit the spread of diseases or whether it should just take its toll [5].

Disease spillover

William Karesh who works for the Wildlife Conservation Society of New York City amplified the need to educate people and increase patrols to fight poaching of apes to avoid transmission of Ebola from apes to humans [5]. An option would be a “hands-off” approach. This would be educating the governments about the effects and costs of too much tourism, the strict prohibition of humans from protected areas, stricter health guidelines in regards to approaching habituated wildlife, health education programs for local populations and staff, and treatment and vaccination approaches for apes [4]. Hygiene and behaviour guidelines for disease spillover include wearing facemasks, limiting visitor times, prohibiting fluid (spitting, defecating) discharge, and distance between human and animal guidelines. Despite they sound promising, there is no data on the efficiency of these measure in preventing disease spillover [4].

Challenges for the development of a vaccine

Animal models such as hamsters, mice and guinea pigs have all been tested for a number of strains of the Ebola virus, yet they do not exhibit the same symptoms humans face. This means that the rodent studies alone are not sufficient enough to develop a human vaccine. Some key things to think about when making a vaccine is how long they can be administered, how long the defence lasts, and how many individuals might be protected after a single intervention [2]. Choosing a vaccine comes downs to what is a cost-effective vaccination strategy because the accessibility of apes is not always easy. It also comes down to whether they are exposed to human contact or not, how to prevent the natural source introducing Ebola into the ape population, and how to stop the spread of Ebola after it has already infected the population. Wild apes that are habituated for tourism or behavioural research are to be regularly observed. Most apes in Africa are not habituated, although a large percentage is habituated in small populations [2]. The population size of apes and the size of the location makes it hard to gain access to the unhabituated apes and monitor them. The somewhat close proximity of habituated apes makes darting a possible route of vaccine administration although it may be difficult and dangerous for the apes and personnel. Unfortunately, there is also the chance that the vaccine was not transferred into the ape [2]. Ideally, a vaccine that protects the ape for many years or decades after a single administration would be advantageous. If a self-spreading, efficient and ethically accepted vaccine is developed, this would reduce the amount of darting and increase the longevity of the protection within a population [2]. Another form of transmission would be through baiting. By developing an orally administered vaccine, it would be less dangerous for both the apes and personnel. The only problem is that some apes may administer more vaccine than others, especially due to the dominant individuals consuming more food [2]. Strategies will need to be formulated to accommodate populations of different sizes, different species, and different habituation statuses and accessibilities [2]. To have more insight into how the wild ape Ebola virus infects apes and also the surveillance of the virus, faeces have been collected from the wildlife. This was a non-invasive way of collecting samples rather than using blood or tissue samples. A non-invasive immunological assay was developed to detect the ebolavirus antibodies in the great ape faeces, which gave scientists the ability to keep surveillance on the virus and help provide information to identify approaches for their protection. Furthermore, it may be valuable information for wild great ape population prospective epidemiological Ebola virus studies [3]. Blood and tissue sampling are not time effective, very costly, and only provide information for a few individuals. Finding carcasses is also difficult because it requires intensive searching, and isn’t sufficient for analyses of viral antigens or nucleic acids due to high degradation. This would then lead to invalid negative results [3].

A government-approved Ebola vaccine has not yet been developed due to many challenges [1]. To test the effectiveness and safety of the vaccine, a randomised controlled trial (RTC) would have to take place, of which thousands of people who are at risk of Ebola exposure, are vaccinated and compared against the controls [1]. It is unpredictable where and when the next outbreak will occur therefore these geographical and practical challenges interfere with testing [1]. The Ebola outbreak from 2014-2016 provided the opportunity to trial the effectiveness and safety of two hopeful vaccines and treatments [1]. Two promising human vaccines against the Ebola virus were developed but did not provide sufficient enough evidence on human trials for licensing. Merck’s vaccine was tested on 800 people within 1 week, including 182 vulnerable contacts to administer Ebola in March 2016 [1]. Merck’s vaccine rVSV-ZEBOV was declared a success in terms of preventing the transmission of the disease through close contact (a “ring” effect) [1]. Nonetheless, the Food and Drug Administration (FDA) was not able to fully license the vaccine due to the lack of convincing data. Janssen’s vaccine was trialled at the end of the 2014/16 outbreak [1]. Janssen wanted to collect data on the body’s Immunogenicity alone, to test how the body responds to the Ebola virus. This meant the data Janssen collected wasn’t entailing that the vaccine prevents illness.

Conclusion

Large epidemics of Ebola viruses has caused a lot of harm to humans and great apes. The likelihood that Ebola will continue to emerge inspires us to protect apes from future outbreaks and to find ways of reducing the amount of contact between apes and humans. The natural circulation of the Ebola virus and the enhancer of the viral emergence needs to be further researched. However, poaching of apes is said to be a source of Ebola transmission to humans. Public education, Ebola awareness, and monitoring of great ape health will be good prevention strategies for the future. The main focus should be developing a vaccine that is delivered safely and efficiently to wild apes in their natural habitats. A deep understanding of the great ape’s natural behaviour and the disease will be necessary for the potential of vaccination programmes [2].

References

  1. Edwards, S. J., Norell, C. H., Illari, P., Clarke, B., & Neuhaus, C. P. (2018, October 19). A Radical Approach to Ebola: Saving Humans and Other Animals.
  2. Leendertz, S. A., Wich, S. A., Ancrenaz, M., Bergl, R. A., Gonder, M. K., Humle, T., & Leendertz, F. H. (2016, December 05). Ebola in great apes – current knowledge, possibilities for vaccination, and implications for conservation and human health.
  3. Reed, P. E., Mulangu, S., Cameron, K. N., Ondzie, A. U., Joly, D., Bermejo, M., . . . Sullivan, N. J. (2014, September 18). A new approach for monitoring ebolavirus in wild great apes.
  4. Ryan, S. J., & Walsh, P. D. (2011, December 22). Consequences of non-intervention for infectious disease in African great apes.
  5. Vogel, G. (2003, June 13). Can Great Apes Be Saved From Ebola?

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Protecting Wild African Apes from Ebola. (2019, Dec 04). Retrieved from http://studymoose.com/protecting-wild-african-apes-from-ebola-essay

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