A timely health check for endangered eastern gorillas

Dr Alisa Kubala3While the world’s attention is currently focused on the Ebola crisis in western Africa, a virus that has been responsible for the deaths of almost one third of the region’s gorillas and many thousands of chimpanzees, as well as humans, in eastern Africa’s Democratic Republic of Congo veterinarian Alisa Kubala’s interest in studying infectious diseases that affect endangered animals, has resulted in a research project that seeks to provide a better understanding of the overall health status of eastern gorilla populations.

It is anticipated the four-year international collaboration will determine if cross-species transmission is occurring in gorilla habitats, and which vector species are responsible for blood parasite transmission.

Kubala’s research involves both examining faeces and blood samples from two endangered eastern gorilla sub-species, Grauer’s (G. beringei graueri) and Mountain (G. beringei beringei), as well as from humans and other primates living in the area, in addition to studying those species of mosquito and fly believed to be responsible for transmitting malaria and microfilariae.

“As humans encroach further into gorilla habitat, the threat of zoonotic disease transmission increases for those species. The project will investigate whether the gorillas are infected by malaria, microfilaria and retroviruses, and if so, the potential health risks associated with the infections,” Kubala, who has previously worked as a vet in Africa but is currently a PhD student attached to the Conservation Medicine Program at Murdoch University’s School of Veterinary and Life Sciences, said.

During October she began the second of the project’s three field studies based in DRC’s Kahuzi-Biéga National Park, where she will spend four months with experienced trackers trekking to gorilla sites in Virunga National Park collecting and studying samples. Her field work is being undertaken in conjunction with Gorilla Doctors, an international team of veterinarians responsible for the healthcare of wild gorilla populations in Rwanda, Uganda and DRC. The last field study will be in the US during 2016, where several collaborating research facilities will help process the foecal samples and establish if malaria is present in gorillas and mosquitos.

Although malaria has traditionally been endemic at lower altitudes, highland areas are becoming increasingly prone to epidemics, raising concerns that the higher temperatures and rainfall due to climate
hange have resulted in increased parasite and vector development and distribution. Kubala has established there are now significant numbers of mosquitos present in the high altitude areas where she works so the capacity exists for gorillas living there to be infected. She said there was also evidence to suggest co-infection with malaria, microfilaria, and retroviruses may lead to increased parasite or viral loads, faster disease progression and increased disease transmission.

“Humans and gorillas share 98.5 per cent of their genetic make-up, which makes them susceptible to many of the same infectious diseases. However, while humans have travelled around the world and built up resistance to many diseases, gorillas remain isolated and immunologically naïve, and are at greater risk of acquiring new infections.”

Multiple species of blood-borne microfilariae are commonly found among humans living near eastern gorillas, and are known to cause clinical illness, but the significance of microfilaria for eastern gorilla health is still unknown.

Gorillas are also under pressure from climate change, wildlife trafficking and the ongoing warfare that is a result of years of political instability in the region, so although exact population numbers are currently uncertain, there are plans for a census to be conducted next year.

Anne Layton-Bennett
The project’s research collaborators also include Kahuzi-Biéga National Park, Virunga National Park, Congolese Institute for the Conservation of Nature, Lwiro Primate Sanctuary, University of Pennsylvania Perelman School of Medicine and Arizona State University Biodesign Institute.

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