A group that provides veterinary care for rare wild mountain gorillas wants to be prepared in case of an Ebola outbreak. Even though a major human outbreak is currently thousands of kilometres away, the group has already thought about vaccinating the gorillas if the threat comes too close for comfort.

Mike Cranfield, the Canadian co-director of the non-profit group Gorilla Doctors, says its member are "very, very concerned" about the risk to gorillas of Ebola.

I'm not sure how available it's going to be now, whether they're holding it back for people. - Mike Cranfield, Gorilla Doctors

The human outbreak centred in West Africa has killed nearly 4,500 people, the World Health Organization reported Wednesday.

But previous outbreaks have killed tens of thousands of gorillas and chimpanzees — a 2002 outbreak at Lossie Sanctuary in northwest Congo alone killed 5,000 gorillas, or 93 per cent of the population at the sanctuary, at the time, a 2006 study reported.

"It's so devastating," said Cranfield. "Where people had gone in before and there was high numbers of great apes ... now they go in and it's completely silent. They can't find any."

Cranfield, who is originally from Peterborough, Ont., was speaking to CBCNews.ca ahead of the debut of Gorilla Doctors, a documentary about his group's work that airs tonight (Thursday) on CBC-TV's The Nature of Things.

There are only about 880 mountain gorillas left in the world, including 450 to 500 that are habituated to humans, and receive monitoring and medical care from Gorilla Doctors. The group also cares for orphaned baby gorillas.

Cranfield said if an Ebola outbreak threatens the gorillas under the groups' care, it will recommend to the governments of Rwanda and the Democratic Republic of Congo, where gorillas live, that the animals be given an experimental vaccine such as VSV-EBOV made by NewLink Genetics. The government's permission would be required to do that.

However, Cranfield later clarified that since the major outbreak of Ebola is so far away, "there is no reason to contemplate vaccination of mountain gorillas at this time, nor have we made a request to any government to do so." An unrelated Ebola outbreak in the Democratic Republic is much smaller. As of Oct. 21, 67 cases and 49 deaths were reported by the Centres for Disease Control and Prevention.

A number of experimental Ebola vaccines have been shown to be successful in monkeys, including VSV-EBOV which is undergoing its first human trials in the U.S. Another, called cAd3 and licensed to the pharmaceutical giant GSK is also in human trials, while an experimental Ebola vaccine developed by Johnson & Johnson's Crucell unit will start human trials in 2015.

Gorilla Doctors co-director Mike Cranfield, left, and his team examine a gorilla named Matashishi. The veterinarians wear masks and protective clothing when handling the gorillas. (Roberto Verdecchia)

Cranfield acknowledged that the current human outbreak might make it hard to get a supply of vaccine for the gorillas.

"I'm not sure how available it's going to be now, whether they're holding it back for people."

Other human illnesses also pose a threat to gorillas, who are susceptible to many of our diseases because they share 98.5 per cent of our genes.

Respiratory disease a leading cause of death

While the leading cause of death for gorillas is trauma, usually inflicted by adult males on infants fathered by other males, the second leading cause is respiratory disease, Cranfield said.

He added that gorillas can get diseases from both other wildlife and from humans. But the "extreme ecotourism" around parks with mountain gorillas that span the border between Rwanda and the Democratic Republic of Congo results in a lot of human-gorilla interaction that can transmit diseases.

Gorilla Doctors treats such illnesses with antibiotics when a gorilla becomes so ill that he or she stops eating. The vets may also consider vaccinating gorillas against some respiratory diseases in the future if scientific evidence supports that, Cranfield said.

In the meantime, the group tries to ensure tourists who get within 20 metres of the gorillas wear masks, and the vets themselves wear protective clothing when handling the gorillas.

Cranfield says that if an Ebola outbreak does reach areas where the gorillas live, he recommends temporarily stopping human ecotours to see the gorillas.

The Gorilla Doctors' work has faced some controversy, as critics question the implications for "wild animals" that receive this amount of medical intervention and human contact.