In just four decades, Ebola has wiped out one third of the world’s chimp and gorilla populations. If it continues, the results will be devastating.
While coverage of the current Ebola epidemic in West Africa remains centered on the human populations in Guinea, Sierra Leone, and Liberia, wildlife experts’ concern is mounting over the virus’ favorite victims: great apes.
Guinea, where the epidemic originated, has the largest population of chimpanzees in all of West Africa. Liberia is close behind. Central Africa is home to western lowland gorillas, the largest and most widespread of all four species. Due to forest density, the number of those infected is unknown. But with hundreds of thousands of ape casualties from Ebola, it’s doubtful they’ve escaped unscathed.
Animal activists are ramping up efforts to find an Ebola vaccine for great apes, but with inadequate international support for human research, their mission could be seen as competing with one to save humans. Experts from the Jane Goodall Institute of Canada insist such apprehension would be misplaced. Two streams of funding—one for humans, one for apes—can coexist in this epidemic, they assert, and must.
“The media was really focusing on human beings,” Sophie Muset, project manager for JGI, says. “But it has been traumatic to [the great ape] population for many years.”
Over the course of just four decades, Ebola has wiped out one third of the world’s population of chimpanzees and gorillas, which now stand at less than 300,000 and 95,000 respectively.
The first large-scale “die-offs” due to Ebola began in the late 1990s, and haven’t stopped. Over the course of just four decades, Ebola has wiped out one third of the world’s population of chimpanzees and gorillas, which now stand at less than 300,000 and 95,000 respectively. Both species are now classified as endangered by the International Union for Conservation of Nature; western gorillas are “critically” so.
One of earliest Ebola “die-offs” of great apes came in 1994, when an Ebola outbreak in Minkébé decimated the region’s entire population—once the second largest in the world. In 2002, an outbreak in the Democratic Republic of Congo wiped out 95 percent of the region’s gorilla population. And an equally brutal attack broke out in 2006, when Ebola Zaire in Gabon (the same strain as the current outbreak) left an estimated 5,000 gorillas dead.
The dwindling population of both species, combined with outside poaching threats, means Ebola poses a very real threat to their existence. To evaluate the damage thus far, the Wild Chimpanzee Foundation is conducting population assessments in West Africa, with the goal of getting a rough estimate of how many have died. Given the combined damage that Ebola has inflicted on this population, the results are likely to be troubling.
In a way, great apes are Ebola’s perfect victims. Acutely tactile mammals, their dynamic social environments revolve around intimacy with each other. Touching hands, scratching backs, hugging, kissing, and tickling, they are near constantly intertwined—giving Ebola a free ride.
In a May 2007 study from The American Naturalist, researchers studying the interactions between chimpanzees and gorillas found evidence the Ebola can even spread between the social groups. At three different sites in northern Republic of Congo, they found bacteria from gorillas and chimps on the same fruit trees. For a virus that spreads through bodily fluids, this is an ideal scenario.
“They live in groups [and] they are very close,” says Muset, who has worked with chimps on the ground in Uganda and the DRC. “Since Ebola transmission happens through body fluids, it spreads very fast.”
For gorillas in particular, this culture proves deadly, making their mortality rate for this virus closer to 95 percent. But like humans, the corpses of chimpanzees and gorillas remain contagious with Ebola for days. While the chimps and gorillas infected with Ebola will likely die in a matter of days, the virus can live on in their corpse for days—in turn, spreading to humans who eat or touch their meat.
It is one such interaction that could result in the spread from apes to humans. But in this particular outbreak, experts have zeroed in on the fruit bat (believed to be the original carrier) as the source. The index patient, a 2-year-old in Guinea, was reportedly playing on a tree with a fruit bat colony.
Whether or not a great ape was involved in the transmission of the virus to humans during this outbreak is unknown. Such an interaction is possible. Interestingly, however, it’s not the risk that great apes with Ebola pose to humans that wildlife experts find most concerning. It’s the risk that their absence poses to the wild.
Owing to a diet consisting mostly of fruit, honey, and leaves, gorillas and chimpanzees are crucial to forest life. Inadvertently distributing seeds and pollen throughout the forest, they stimulate biodiversity within it. Without them, the biodiversity of the vegetation may plummet, endangering all of the species that relied on it—and, in turn, the people that relied on them.
“They are not the only ones who act as seed dispersers,” says Muset. “But they are the big players in that field. So when [a die-off] happens, it can decimate an entire forest.”
Wildlife experts worldwide are working to raise both awareness and funds for a vaccination process. It’s a battle that she says was gaining speed last January, when a researcher announced that he had found a vaccine that could work in chimps But as the epidemic in West Africa grew, the focus shifted.
But Muset says its time to return to the project. “There is a vaccine, but it has never been tested on chimpanzees,” she says. “Progress has been made, and preliminary testing done, but testing in the field need to happen to make it real.”
As to the question of whether it’s ethical to be searching for a vaccine for wild animals when humans are still suffering as well, Muset is honest. “For sure there is a direct competition here. But wildlife and humans have a lot of diseases in common that they can transmit from one to the other,” she says. “And I think you can think of it as two streams of funding, one to wildlife and the other to human beings.”
While it’s great apes that wildlife experts are seeking to save, human nature as a whole, Muset argues, is at stake. “If you want a healthy ecosystem, the more you have to invest in health for wildlife and humans,” she says. “Then, the better place it will be. Because really, it all works together.”