Over the last 20 years, the wild populations of many of the world’s great apes have drastically declined. Recent surveys have suggested that several species of large primates, including chimpanzees, orangutans and gorillas, have experienced severe losses in population numbers. Now, some conservationists say that vaccinating great apes against diseases like the Ebola virus might be the quickest and most effective short-term step towards saving them from extinction.
Despite the efforts of conservationists working with governments to establish nature reserves and sanctuaries where our primate cousins are protected from poachers and habitat loss, the spread of diseases can have a large impact on struggling great ape populations. According to a new report by the Wildlife Conservation Society, Flora and Fauna International and the Congolese Institute for the Conservation of Nature, the eastern lowland gorilla population alone has plummeted from 17,000 in 1995 to about 3,800, Dominique Bonessi reports for the PBS Newshour.
But while war, poaching and habitat loss are some of the worst human-related causes blamed for the population drop, diseases like Ebola have killed tens of thousands of great apes in recent years, Robin McKie reports for The Guardian.
“I did a survey of the impact of Ebola over the past 20 years and found that about a third of the world’s gorillas were wiped out by the disease,” Peter Walsh, a primate ecologist at Cambridge University tells McKie. “The key point is that the disease—which was probably spread by bats—killed gorillas and chimps in remote strongholds where we thought they were safe.”
Over the the last few decades since the Ebola virus was discovered, researchers believe that the virus may have killed almost a third of the world’s wild gorillas and chimpanzees. Since the late 1990s, biologists have attributed several large die-offs of great apes in Gabon and the Republic of the Congo to Ebola outbreaks, Caleb Hellerman reported for The Atlantic in 2015.
And while gorillas sanctuaries in countries like Rwanda and Uganda have become popular tourist attractions, those animal-loving visitors can sometimes unintentionally bring new diseases with them, McKie writes. But some biologists like Walsh believe that vaccinating the great apes against diseases could give them a protective buffer against human-spread diseases.
“Our research has made it clear that viruses such as Ebola can affect gorillas and chimps, as can human respiratory viruses,” Walsh tells McKie. “Within five years, I would want all gorillas and chimpanzees that come anywhere near humans to be vaccinated against Ebola or respiratory diseases. That is the only way we can go.”
This is easier said than done. Despite their size, gorillas are incredibly shy and many vaccines designed for great apes are only viable via injection. While Walsh has spent years trying to develop an oral vaccine to guard chimps against Ebola, new limits on live-animals tests in lab settings could present new difficulties in developing better vaccines, Hellerman wrote. While Walsh plans on testing an Ebola vaccine on wild apes this summer, he says time is of the essence in protecting the primates from devastating diseases.
“Unless we do something now, great apes will no longer be part of the functioning ecosystems of Africa or of Asia,” Walsh tells McKie. “Their populations will be so small and isolated, and they will have to be managed so carefully, that they will only be able to exist on land that is run like a zoo or a park.”