Gorilla Medicine

Only about 900 mountain gorillas—the animals protected by Dian Fossey of Gorillas in the Mist fame—remain in the wild. But the few will probably “be just fine,” largely because veterinary care is now a mainstay in their peaceable kingdom, says Chris Whittier, V97, who has treated gorillas in six national parks in Africa.

Fossey’s work paved the way for the creation of organizations like the Mountain Gorilla Veterinary Project so that veterinarians, including Whittier, director of the master’s program in conservation medicine at Cummings School, can continue to protect the endangered species.

Wildlife veterinarians, staff at four national parks, ecotourism operators and other nongovernmental partners work together to monitor the mountain gorilla population in the Virunga Mountains and Bwindi Forest in east central Africa. They treat gorillas’ health problems, ward off poachers, conduct behavioral research and work with the locals to safeguard the animals and their habitats.

“Because of the history of all those partners, you can actually distinguish the gorillas in that overall population that haven’t had veterinary care and quantify how much a difference veterinary care has made,” says Whittier, who worked with the Mountain Gorilla Veterinary Project first as a Ph.D. student in population medicine at North Carolina State and then as a staff veterinarian from 2001 to 2006. (That program now operates as Gorilla Doctors, a partnership between the Mountain Gorilla Veterinary Project and the Karen C. Drayer Wildlife Health Center at the UC Davis School of Veterinary Medicine.)

A study published in PLOS One in 2011 found that gorilla populations that received veterinary care in addition to protection from poachers grew by 4 percent, while the groups that had anti-poaching protection but no veterinary care expanded by 2 percent. Gorilla populations that received neither care nor protection declined 2 percent. Felicia Nutter, V93, an infectious disease and global health specialist at Cummings School who also worked for Gorilla Doctors (and is married to Whittier), was a co-author of the study.

Because gorillas have no natural immunity—and share 98.5 percent of their genes with humans—they are susceptible to our diseases, such as the flu and measles. That’s partly why Fossey was a staunch opponent of gorilla tourism for years. To reduce the risk of disease transmission between people and gorillas, Gorilla Doctors organizes annual health screenings, vaccination clinics and follow-up health care for the hundreds of rangers, trackers, researchers and others who routinely share the animals’ habitat.

The Elusive Lowland Gorillas

Even though the mountain gorillas are a conservation medicine success story, “the real challenge is how to apply that work to other gorilla, chimpanzee, orangutan and primate populations,” Whittier says.

For example, the populations of eastern and western lowland gorillas far outnumber Fossey’s beloved mountain gorillas. Western lowland gorillas, the kind found in zoos, number around 100,000 in the wild—100 times the number of mountain gorillas. An estimated 5,000 to 20,000 eastern lowland gorillas are left in the wild.

Despite their large numbers, Whittier says the lowland gorilla subspecies are at enormous risk for extinction, partly because of disease. Ebola alone is estimated to have killed about one-third of the western lowland gorilla population, according to the World Wildlife Fund (WWF).

Lowland gorillas are also targets for bush-meat hunters, says Whittier. “And even within protected national parks, they’re living in places where there’s a lot of logging and mining. Huge areas of forests are being cut down to get all the ingredients that go into our cellphones and other electronics, as well as our hardwood furniture.”

Unlike the mountain gorillas, which live in national parks that can be walked in a day, lowland gorillas inhabit the vast Congo River basin, an area larger than the state of Alaska. They range widely and are much more difficult to track, habituate and monitor than mountain gorillas, particularly because they are naturally wary of humans, given their long history of being hunted.

Blow-Dart Medicine

Because of the fearful and elusive nature of the western lowland gorillas, it was unclear whether the successes in preserving the mountain gorillas could translate to this species. In 2011, the WWF agreed to let a team, which included Whittier, try at its field site in the Dzanga-Sangha Protected Areas in the Central African Republic. The WWF has managed to habituate two groups of western lowland gorillas there and is in the process of habituating two more.

Whittier first administered a measles vaccine—via blow dart—to protect the gorillas from catching the highly infectious disease from people and to prove it was possible to safely conduct a vaccination campaign.

“There were a lot of unknowns,” he says. “Could we even get close enough to dart them? If so, were they all going to run away? Were they going to try to bite us?” (A 250- to 400-pound gorilla can crack a coconut in its mouth.)

With the help of the Central African Ba’aka, a nomadic Mbenga pygmy people who work with WWF, Whittier and the team were able to track and individually identify the gorillas for vaccination—while circumventing forest hazards, such as trampling elephants, buffalo and bongo (a type of antelope). “The Mbenga people really make all this work possible,” says Whittier.

The darting went off without a hitch, and Whittier’s team followed up by treating Dzanga-Sangha gorillas for a respiratory infection. “With these outbreaks, you can almost never know if [these illnesses] are natural or if they are something they are getting from people,” he says. “The underlying cause is usually viral, but a secondary bacterial infection that capitalizes on that underlying infection can be devastating for these animals, so we proactively treat them with antibiotics.”

They also removed a snare from a young male gorilla. “The traps are not intended for the gorillas, which are strong enough that they can usually break the wire or rope snare from whatever it’s attached to,” Whittier says. “But then they are stuck with whatever is caught around their hand or foot, and that slowly cuts off the circulation. Those hands and feet either fall off or get infected, and the animals can die unless you can put them under anesthesia to remove the snares.”

Whittier returned to the Central African Republic in May to assist WWF in its efforts to confront the latest threat to the lowland gorillas: anthrax. Two years ago, his team used blow darts to vaccinate the animals against the disease after a dead gorilla tested positive for anthrax. The lethal bacterium primarily infects animals that eat grass, but anthrax also can be found in predators or animals that scavenge their carcasses. Veterinarians don’t know why lowland gorillas—which traditionally dine on fruit, leaves, bark and rotten wood—would die from anthrax.

Political instability in the region exacerbated the threat to the lowland gorillas. A week after Whittier returned to the United States after the first anthrax vaccination campaign in 2013, there was a military coup in the Central African Republic, one of five successful coups that have occurred since the country won its independence from France in 1960. “I managed to leave on the second to last flight,” he says.

Whittier has been eager to return, noting that a lack of veterinary care has serious consequences for the endangered gorillas. “The anthrax vaccination is supposed to be given to domestic livestock every year,” he says, “and since that first gorilla died, the threat of anthrax has not gone away.”

This article first appeared in the Summer 2015 issue of Cummings Veterinary Medicine magazine.

Genevieve Rajewski, the editor of this magazine, can be reached at genevieve.rajewski@tufts.edu.