Ebola: Human Health and Conservation

A new test, reported in the news last week, is being developed for quick and easy detection of ebola, dengue fever and yellow fever. The standard test currently being used consists of a polymerase chain reaction (PCR) or antibody-capture enzyme-linked immunosorbent assay (ELISA). These current tests however take time, a major limiting factor when deciding whether to quarantine a patient. The new test acts similarly to a pregnancy test, with disease specific antibodies rapidly binding to coloured particles if present.

Whilst this test is less accurate than standard protocols, it's an amazing step in the right direction for remote medical centres, with limited resources and even more limited time to help combat this devastating disease. As of July 2015 there had been 27,609 human cases and 11,261 human deaths caused by the disease. Thankfully research efforts have led to the development of this rapid test that may help limit the situation. Ebola is however more than just  a human disease, it is also a wildlife conservation issue, and this side of the disease is little reported.

Emerging diseases, alongside habitat loss and poaching, are a major threat to great apes such as the chimpanzee and gorilla. Some diseases are naturally occurring in primate populations, some are introduced by other wildlife reservoirs, and others are a result of human introductions. There are massive benefits to the habituation of chimpanzee and other ape species groups, to enable detailed research to be conducted, to earn revenue from ecotourism, and to indirectly reduce poaching efforts. The risks that come with this habituation are however high, leading to increased risk of disease transmission between humans and other apes.

Ebola haemorrhagic fever is a viral disease, first detected in Africa in the 1970s. The virus belongs to the family Filoviridae, with 5 species being identified to date, with the 2014 outbreak being caused by the Zaire species.  

In the past 20 years or so, the Zaire strain of ebola has killed around one third of the global gorilla population and just less than this of the chimpanzee population. Not only this, but a study conducted a few years back used models based on real data to show that a single disease outbreak could take gorilla populations between 5 years (low disease outbreak, 4% of population effected)  to over 130 years (high disease outbreak, 96% of population effected) to recover. These were in fact conservative estimates, as a single outbreak would be unlikely in habituated populations experiencing repeated exposure to humans.

Disease exposure is therefore an important conservation issue for great apes; a threat that definitely needs to be addressed. The solution is some what of a balancing act, the revenue and interest gained from ecotourism is vital for ape conservation, and yet exposure to humans is also of detriment. Certain rules for tourists to adhere to include wearing masks, having short visitation durations and keeping a certain distance away from primate groups. None of these actions have however been tested to determine what exactly constitutes a safe distance etc. The number of diseases that can be transmitted between humans and other great apes are fairly vast. What may seem like two separate problems: disease outbreaks in humans and conservation issues in apes are of course linked, but the costs of vaccinating local communities against diseases that may impact apes, against directly vaccinating apes, again must be balanced.

For more information on research investigating chimpanzee behaviour, evolution & conservation issues, check out the Jane Goodall Institute website here.