The Ebola threat for gorillas

18 November 2014

Interview with

Dr Peter Walsh, University of Cambridge

Alongside humans, gorillas can catch Ebola too. But unlike bats, who Baby gorilladon't get symptoms, gorillas get infected much the same way humans do. It's estimated that a third of gorillas have been wiped out by the deadly virus. Peter Walsh is a primate quantitative ecologist from Cambridge University, and he explained to Kat Arney what is happening to our primate cousins...

Peter -   Gorillas and chimps are our closest relatives and their immune systems are extremely similar to ours.  And therefore, when a gorilla gets Ebola, it behaves pretty much the same way as it would if it was in you or me.

Kat -   So, they're getting all the horrible fevers as we had described, the bleeding and all the kind of horrible stuff.

Peter -   Absolutely, yeah.  It's even worse for them because think about it-  They're out in forest.  There's no nurses.  They don't get any water.  they don't get protected from other animals.  It's pretty horrific.

Kat -   What do we know about how these wild chimp and gorilla populations are getting Ebola?

Peter -   Best guess is that fruit bats eat fruit and gorillas eat fruit.  So, they go to the tree and some bats have been there and left the virus in their body fluids, maybe saliva, maybe faeces, and they eat the fruit, and then they get infected.

Kat -   How widespread is this problem?  I mean, are we seeing animals being affected in the areas where the current outbreak is?

Peter -   The biggest mortalities of gorillas and chimpanzees have been in central Africa which is quite away from these outbreaks.  But there are chimpanzees in the area where that first index case that Suzy was talking about, it was in Guinea, in a remote area.  Where this outbreak started was in the most forested area in west Africa and there are still some chimpanzees and other animals like monkeys out in that area.

Kat -   So basically, we just don't know.

Peter -   West Africa, we don't know.  Central Africa, we have a pretty good idea.  We have actual evidence where we have somebody who got sick and they told us, "Well, I ate a gorilla" and they went out found the carcass and they found the same virus in the gorilla carcass that the person had.  So there, it's pretty well documented.

Kat -   Is there anything that can be done?  I mean, it does sound like this disease is decimating these wild primate populations?

Peter -   Well, because our immune systems are so similar to gorilla or chimpanzee, it means that the vaccines that work on us, work on them too.  Now, I actually led a captive chimpanzee vaccine trial with Ebola vaccine.  Not one of the ones that you already talked about, but a different one.  The vaccine didn't cause the chimpanzees any kind of the side effects and it caused a very robust immune response.  Right now, I'm trying to gear up with some colleagues to go out and vaccinate gorillas in the wild.

Kat -   That's going to be a bit tricky though, surely?

Peter -   It turns out to be a lot easier than you think.  it's easy for these...

Kat -   You have to catch and stab them?

Peter -   No, you don't have to catch them.  We use a blowgun.  So, you don't actually have to immobilize them.  It's easy for the ones that are in the tourism programme, or a research programme.  It's kind of fun.  It's kind of scary.  You get the silver back and you think - people were certain that the gorillas are going to kill us when we did it.  We went out and did it with measles vaccine and they didn't hardly respond at all.

Kat -   It's like, I don't even notice.  It's like a mosquito bite or something I guess.

Peter -   Yeah.  Go and Google gorilla and teeth and you'll see, they bite each other all the time.  that's a lot worse than a little needle.

Kat -   I mean, we've mentioned that the fruit bats might be the reservoir for Ebola in the wild.  Is there any way we can eradicate that?  How do we go about trying to track down that reservoir?

Peter -   It's going to sound like science fiction, but 50 years from now, it's going to be standard practice.  It's what's called a self-disseminating vaccine.  What it does is you take a different virus, you pull a little piece of Ebola in that other virus and then you give that virus to the bats and then it spreads within the bat population and immunizes the bats.  There's research in other species on this self-disseminating vaccines going on right now.  Eventually, that's the way we're going to handle wild life vaccines.  Right now, the state of the art is oral vaccination.  You put the vaccine to a bait.  This have been very effective in Europe and almost eradicating fox rabies.  You put baits out, the animals eat it and they get immunized.  But that's the kind of thing that we could do.

Kat -   When it comes to actual people rather than these chimps and gorillas, what are your feelings on the outbreak and how it's being handled?

Peter -   What Colin was talking about is very true, if you don't respond quickly then you have a problem.  In this case, sort of institutional rivals, international rivalries, it started in the French speaking country.  The French don't like the Americans.  The Americans had better capacity to do this sort of modelling thing.  the World Health Organisation doesn't like the Centre for Disease Control from the United States.  The reason this thing got out of control was that those national and international organisations could not play well together and they let it get out of control.

Kat -   Do you have hope personally that it may get back under control?

Peter -   Right now, I've been doing some projections.  It's difficult to tell right now whether it's going to - Liberia has slowed down a little bit and is looking a little bit better but Sierra Leone and Guinea are still moving along.  It's still a chance that we're going to have really, really nasty outbreak of the kills, up until about hundred thousand people or more, just unclear.

Kat -   That's pretty terrifying vision of the future.  So, I really hope that some of the vaccines and treatments that we've been talking about do come online soon.  Are you hopeful for those as well?

Peter -   I'm actually doing some modelling on how much it's going to take, how much vaccine it's going to take.  It's looking like it just depends.  If it really goes big then the vaccines are the only thing that's going to stop it.  And they will be in production in large number of doses by about April to do that.  If it attenuates then the vaccines are going to be too late.

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