Science Interviews


Tue, 18th Nov 2014

The Ebola threat for gorillas

Dr Peter Walsh, University of Cambridge

Listen Now    Download as mp3 from the show Inside the Ebola Epidemic

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.  Itís even worse for them because think about it-  They're out in forest.  There's no nurses.  They donít get any water.  they donít get protected from other animals.  Itís 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 donít know.

Peter -   West Africa, we donít know.  Central Africa, we have a pretty good idea.  We have actual evidence where we have somebody who got sick and they told us, ďWell, I ate a gorillaĒ and they went out found the carcass and they found the same virus in the gorilla carcass that the person had.  So there, itís 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 didnít 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 -   Thatís going to be a bit tricky though, surely?

Peter -   It turns out to be a lot easier than you think.  itís easy for theseÖ

Kat -   You have to catch and stab them?

Peter -   No, you donít have to catch them.  We use a blowgun.  So, you donít actually have to immobilize them.  Itís easy for the ones that are in the tourism programme, or a research programme.  Itís kind of fun.  Itís kind of scary.  You get the silver back and you think Ė 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 didnít hardly respond at all.

Kat -   Itís like, I donít even notice.  Itís 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.  thatís a lot worse than a little needle.

Kat -   I mean, weíve 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 -   Itís going to sound like science fiction, but 50 years from now, itís going to be standard practice.  Itís 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, thatís the way weíre 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 thatís 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 itís being handled?

Peter -   What Colin was talking about is very true, if you donít 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 donít like the Americans.  The Americans had better capacity to do this sort of modelling thing.  the World Health Organisation doesnít 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.  Itís difficult to tell right now whether itís going to Ė Liberia has slowed down a little bit and is looking a little bit better but Sierra Leone and Guinea are still moving along.  Itís still a chance that weíre going to have really, really nasty outbreak of the kills, up until about hundred thousand people or more, just unclear.

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

Peter -   I'm actually doing some modelling on how much itís going to take, how much vaccine itís going to take.  Itís looking like it just depends.  If it really goes big then the vaccines are the only thing thatís 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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