THE news for the world’s amphibians has not been good over the last few years. The chytrid fungus has caused large reductions in amphibian numbers over wide geographical areas and left many populations vulnerable. Now there appear to be two new emerging disease threats to Europe’s numerous species which may have an even more devastating effect.
Firstly, a report published in the journal Current Biology describes how several new strains of Ranavirus have been isolated in recent years from dying amphibians in northern Spain. What is especially worrying is that the viruses appear to be able to jump between frogs, toads and newts.
In the Picos de Europa National Park, for example, the common midwife toad, the common toad and the alpine newt have all suffered major population declines and all the common amphibian species within the park have experienced outbreaks of disease with variable mortality.
The Ranaviruses involved can cause ulceration of the skin as well as widespread internal haemorrhage and there is already evidence that the viruses have spread to parts of France and the Netherlands. Also of concern is that the virus may be able to infect reptiles as there is a documented case of a snake being infected after feeding on infected amphibians. As if the above news is not bad enough, another report, this time published in the journal Science, concerns the parasitic fungus Batrachochytrium salamandrivorans.
First recognised in the Netherlands in 2013, where it was blamed for killing all but 10 of the country’s fire salamanders, it is now thought to be capable of fatally infecting a wide range of Europe’s newt and salamander species.
The fungus lives on the skin and causes severe ulceration followed by death within a matter of weeks. Researchers into the disease have concluded that the origin of the fungus is likely to be various species of Asian salamanders imported to supply the pet trade.
No Asian salamanders have been found to be susceptible to the fungus and studies suggest that they have lived in harmony with it for some 30 million years.
European salamanders, on the other hand, appear to have no resistance to the infection.
A likely culprit
One of the most likely culprits for bringing the disease to Europe is the Chinese fire-bellied newt which is a popular pet worldwide. Millions of these newts have been transported across the world in the last decade and so the opportunities for dissemination of disease are numerous. And whilst B. salamandrivorans has not yet been seen in the wild outside Belgium and the Netherlands, there is a very real likelihood that it will spread.
If the disease should arrive in Britain then all three native species of newt – common, palmate and great crested – are likely to be susceptible. The last of these is already rare and has substantial protection under British conservation legislation. The danger posed by imported infections, be they viral or fungal, is very real and potentially catastrophic.
The transport of animal disease around the world and the danger posed by it to domestic stock is well documented. There are now clear indications that the same can be true for disease that affects wildlife.
Anyone who has visited Australia or New Zealand will be aware of the strict checks undertaken on entry to those countries to ensure that no exotic plants or animals are imported illegally.
Here in the UK we have been notably lax in this respect over many years and have paid little more than lip-service to the prohibitions.
For the sake of our wildlife and our domestic livestock, it is probably time for a sea-change in our attitude to the importation of alien species and the diseases that they may carry.
