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October 27, 2008
From wildlife to civilization: Primate disease ecologist tracks germs in the wild

By carol clark

A chimpanzee once turned Thomas Gillespie into a yo-yo while he was ascending a tree with a rope and harness. “Chimpanzees have 10 times the strength of a man and they like to play with you when you’re on a rope,” he says. “They’ll grab it and bounce you up and down.”

There is no typical day at the office for Gillespie, assistant professor of environmental studies and one of the world’s leading primate disease ecologists, with research projects ongoing in Congo, Uganda and Tanzania.
“One of the most harrowing things you will ever experience is having a full-grown, male silverback gorilla get in your face when he feels threatened. You can feel and smell his breath,” he says.

The male gorillas beat their chests and use other displays of their immense power to warn intruders that they mean business. But the animals are peaceful vegetarians that rarely attack. “You’re completely humbled in their presence,” Gillespie says. “It takes you to the core of some of the things we’re still dealing with as a species — having power and being able to use it wisely.”

Gillespie left the University of Illinois to join Emory this fall. He was recruited by the Global Health Institute and his mentor, Chair of Environmental Studies Uriel Kitron, who is helping build the University’s reputation as a global leader in disease ecology.

Gillespie tracks the ecology of pathogens in the wild to learn how they may jump between nonhuman primates and humans. While HIV/AIDS and Ebola are the two most dramatic examples of diseases linked to wild primates, many other viral, bacterial, fungal and parasitic pathogens found in apes and monkeys are readily passed to humans.

“The close genetic relationship between wild primates and people, coupled with growing human activity in forests, is increasing the chances for the exchange of pathogens,” he says.

Logging in gorilla habitat, for example, may have contributed to outbreaks of Ebola in Central Africa. The loggers take most of the trees, leaving the damaged hollow ones that are inhabited by bats, the likely reservoir of the Ebola virus. Gorillas come to feed on the fruit from the few remaining trees, bringing them into more frequent contact with bats and their guano. Not only has Ebola devastated communities of endangered gorillas and chimpanzees, poachers who butcher an infected ape can spark outbreaks among humans.

Gillespie is investigating sites where logging was done during the 1960s, as well as sites of present-day logging. He gathers fecal and blood samples from people and primates while also scouring the forest floor and treetops to learn about the diversity of pathogens in the environment. The data is mapped spatially and over time, and compared with data from undisturbed forests.

“One approach is to deal with a pathogen after it becomes a major threat to people, then develop a vaccine,” Gillespie says. “But disease ecologists look at the evolution of pathogens in their natural systems. We’re gathering data to help reduce the risks of a pathogen jumping from animals to people and vice versa. And if a pathogen does make the jump, we want to have enough data to develop effective interventions.”

The National Geographic Society is funding one of Gillespie’s research projects in the Republic of Congo, which could yield data to develop more sustainable logging methods, and protect the health of people and wild primates.

Gillespie is among the founding scientists of the Great Ape Health Monitoring Unit, a cooperative effort of the United Nations, academic institutions and non-governmental organizations. The unit strives to integrate research from anthropologists, health professionals, biologists, ecologists and other scientists who are studying wild primates in remote locales with the work of lab-based scientists and computer modelers.

“There is growing awareness that the majority of emerging pathogens in the world are coming from wildlife. And most of that wildlife is in tropical forests — in places where we have the least disease surveillance,” Gillespie says. “By giving researchers from a range of disciplines standardized guidelines for collecting data, and integrating that data across sites, we can build a baseline for pathogen patterns in primates. That may give us a chance to see something abnormal before it becomes an epidemic.”