Ebola Is Wiping Out the Great Apes as Scientists Race for a Cure

The disease has killed off a third of the western gorilla population.

(Photo: Brent Stirton/Getty Images)

Feb 2, 2015· 2 MIN READ
Katharine Gammon has written for Nature, Wired, Discover, and Popular Science. A new mom, she lives in Santa Monica.

As the Ebola epidemic ebbs among humans, the disease continues to take a staggering toll on chimpanzees and gorillas.

For instance, the virus has killed about a third of the western gorilla population over the past 20 or 30 years, said Peter Walsh, an ape researcher and a conservationist at the University of Cambridge in the United Kingdom.

“The impact has been more severe on gorillas,” said Walsh. “They die at a higher rate—between 95 and 97 percent—in outbreak areas.”

Chimpanzees fare slightly better in battling Ebola, partly because they live in a larger swath of Africa. Walsh points out that both chimps and gorillas face a host of threats—including poaching and habitat loss.

There’s a quick fix for Ebola, though, in the form of vaccines. Walsh was part of a team that last year successfully developed an Ebola vaccine for captive chimpanzees.

He suggested a three-pronged approach to help animals in the wild survive the virus. The first is to vaccinate apes using a dart gun.

“We’ve already tried that out; it works very well—the gorillas don’t mind it much,” said Walsh. In the longer term, he suggests an oral vaccine placed in a bait trap, a technique that was used with fox populations to protect against rabies in Europe.

The third, most ambitious of the vaccine strategies is to create a self-replicating vaccine that would make the apes immune to Ebola.

The idea is to use a species-specific virus that all wild gorillas and chimps already carry to deliver the vaccine. After some gorillas or chimps get the vaccine, they spread the infection to others, creating immunity around the community.

“It’s hard to get everyone with a blow pipe, so if they’re not habituated or in a research program, it’s hard to get close,” he said. “That makes the self-disseminating vaccines our best hope.”

Walsh knows that there are questions still to be answered about the potential for such a virus-borne vaccine to mutate in the wild. Still, he said that the vaccine strain is no more likely to mutate than the strain that the apes already carry.

“None of the infectious parts of Ebola are included in the vaccine, so there is no chance that you would get some sort of recombinant super-virus,” he said. “We are conservationists, and we are not going to recklessly do something dangerous.”

Ebola isn’t the only disease that humans and apes share.

“Human respiratory viruses are the number one cause of death; they cause half of deaths in chimps and gorillas that are in tourism and research programs—particularly in programs where people get close,” he said. “People get on a plane, catch a classic international travel cold, they go to chimp sites and cough on them, and the apes get it and they die.”

Walsh hopes that in the future, vaccinating wild apes won’t be a controversial undertaking. He said that the human outbreak has sensitized the world to Ebola, and the facilities to do the trials are up and running. All that’s left is to find the funding to test out the drugs.

“People are forgetting that our closest relatives are being wiped out, and we’re losing them at an astounding rate,” said Walsh. “I hope that this Ebola outbreak helps a little bit to bring that back into frame.”