Ebola-like virus wipes out amphibians

An ebola-like virus is wiping out frogs and other amphibians in Spain...
20 October 2014

Interview with 

Stephen Price, University College London




Recently, frogs, toads and newts in the Spanish National Park Picos de Europa have been dying in unprecedented numbers from a horrible disease which Treefrogmakes them bleed internally and which can only be described as frog Ebola. 

At the heart of this illness are agents called ranaviruses.  These usually infect only amphibians but, unlike previous ranaviruses infections which have targeted one species, these new viruses  are indiscriminately killing all kinds of amphibians and even reptiles that prey on the infected frogs and toads.  Stephen Price from University College London explained to Kat Arney what had been going on...

Stephen -   In 2005, the first observed mass mortality events were noted by rangers in the park.  Severe disease across the entire amphibian community, so systemic haemorrhaging in all six common species of amphibian which are found in the National Park.  The virus seems to affect most of the major tissues, also systemic haemorrhaging which effectively means bleeding from everywhere.  And so, the amphibians can vomit blood and it can come out at both ends.

Kat -   In this paper, what exactly were you looking at and what did you find?

Stephen -   First question was, what's causing these infections?  We found a fairly novel lineage of ranavirus which seems to have pre-exisiting capacity to infect all amphibian species present in the Picos de Europa.  Also, we report on a snake which have been feeding on the amphibians and also died.

Kat -   What does your research tell us about where these viruses might have come from?

Stephen -   It's a tough question to work out the origins of these viruses at the moment, but the fact that these viruses are quite closely related to some Chinese viruses says that there's a real long distance international component to virus movement.

Kat -   Frogs don't tend to move internationally.  So, what do you think might be spreading this virus?

Stephen -   We've seen almost simultaneous emergence at multiple sites in the Picos de Europa which is separated by many miles of rugged mountainous landscape.  And so, that picture like you say is not consistent with a picture of amphibian dispersal moving this far around.  You need to factor in something else and when you consider the pattern of relatedness of the virus in a global context, and other things that we know about ranavirus translocations globally.  So, the presence of ranaviruses in traded and farmed amphibians, it suggests that there's an important role for humans in bringing these viruses into that region.

Kat -   This sounds pretty bad news for amphibian populations if there's this virus spreading incredibly quickly across the globe, possibly moved by humans and it's causing a destruction of lots of different species.  What can we do about it?

Stephen -   It's a fairly grave situation, a really serious picture for amphibians.  So, it's difficult to know how to tackle infections at wild ponds once they're established, other than removing all the animals that are infected from the site, which is a really tough ask and probably wouldn't be very popular anyway.  So, I think the best way forward that I can see and that I can impact on is to try and get a better understanding of how these viruses are moving both globally and locally.  And so, that's definitely something that I'll be looking to pursue with my research.


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