Chimpanzee studies highlight disease risk to all endangered wildlife

Famed primatologist Jane Goodall with Emory disease ecologist Thomas Gillespie, who is working with the Jane Goodall Institute to study the health of chimpanzees in Tanzania's Gombe National Park.

The American Journal of Primatology just published a special edition bringing together experts who have contributed to the understanding of chimpanzee health at Gombe National Park in Tanzania and beyond. Gombe is the site where Jane Goodall pioneered her behavioral research of chimpanzees. Goodall’s work at Gombe began in 1960, and continues today through the Jane Goodall Institute, making it the longest field study of any animal.

Thomas Gillespie, associate professor in Emory’s Department of Environmental Sciences, was a guest editor of the special journal edition, along with fellow scientists Dominic Travis and Elizabeth Lonsdorf. Gillespie works at the interface of biodiversity conservation and global health. Much of his research examines how and why anthropogenic influences within tropical forests alter disease dynamics and place wild primates, people and other animals in such ecosystems at increased risk of pathogen exchange.

Following is an interview with Gillespie about the special journal issue and why research on chimpanzee health is important.

What is the current status of chimpanzees?

Both the common chimpanzee and the bonobo, the two chimpanzee subspecies, are endangered. Chimpanzees are the most closely related species to humans and we see them declining precipitously due to habitat loss and poaching. Typical estimates for the chimpanzee population are in the hundreds of thousands. That’s far less than the number of people in Atlanta for the entire chimpanzee species spread across all of Africa. There is a real risk of chimpanzees going locally extinct in core parts of their habitat. Chimpanzee communities in West Africa, for instance, have very little habitat left. They’re often found living in scraps of habitat between villages.

How important is health to conservation? 

Wildlife health is a critical conservation issue, but that’s something that’s only recently been recognized. Wildlife populations already dealing with poaching and habitat loss are more vulnerable to being knocked out by disease. It becomes even more difficult when they are exposed to new pathogens, from humans or domesticated animals.

On top of that, primates are dealing with shifts in the dynamics of pathogens like Ebola. Ebola’s been around for a long time in natural systems but now we’re seeing big mortality events in wild chimpanzees and other apes. The Lowland Gorillas are actually listed as critically endangered due to Ebola.

How did you become involved with Gombe and the Jane Goodall Institute?

Fifteen years ago, as evidence mounted that disease was playing an important role in the population declines observed in Gombe chimpanzees in Tanzania, Dominic Travis and Elizabeth Lonsdorf developed a prospective health monitoring system. They began to collect specific behavioral data on signs of respiratory and gastrointestinal illnesses, combined with body condition scoring on a monthly basis for the chimpanzee communities at Gombe, that paralleled efforts by the Mountain Gorilla Veterinary Project in Rwanda and Uganda.

When I met Dom and Elizabeth at a workshop in Germany in 2004, I was six years into efforts to understand how logging and forest fragmentation in and around Kibale National Park, Uganda, affected disease dynamics in resident primates. My findings in Uganda highlighted that some forms of anthropogenic disturbance can alter the dynamics of natural pathogens in wildlife, such as a legacy of selective logging. It also revealed that other forms of disturbance, such as active forest fragmentation, can lead to opportunities for pathogens to jump between species, including the introduction of pathogens from people and domesticated animals to wild primates.

Dom and Elizabeth asked me to join their effort and expand the scope of their project to a One Health approach. I initiated diagnostic surveillance linked to geographical indicators of species overlap for Gombe’s chimpanzees and baboons, as well as the people and domesticated animals within the Greater Gombe Ecosystems. It serves as a map of all the places these species are interacting, for a greater sense of how transmission may be occurring. Integration of these new data streams, along with the ongoing observational health data and in-depth post-mortem necropsies, have allowed us to establish baselines of health indicators to inform outbreak contingency plans.

Dom, Elizabeth and I now co-direct this effort, which is known as the Gombe Ecosystem Health Project.

How does Gombe fit into the bigger picture of wildlife conservation? 

As a result of Jane Goodall’s initial observations of disease outbreaks impacting Gombe’s chimpanzees, it became apparent that infectious diseases have the capacity to threaten the conservation of endangered species.

Some people call Gombe “a living laboratory.” It’s unique in the sense that it’s a place where there has been long-term data collection on the behavior patterns of chimpanzees, and for the past 15 years we’ve been collecting all this data on their health.

Methods have been developed at Gombe that allow us to monitor chimpanzee health non-invasively, through fecal sampling, so that we don’t have to dart the animals and tranquilize them to take blood samples. Many of the tools and approaches developed at Gombe have the capacity to manage disease-related threats to other wildlife populations globally.

Ashley Sullivan from the Jane Goodall Institute contributed to this report.

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