Deadly Chytrid fungus introduced into Mallorca from captive breeding23/09/2008 11:18:17 Captive breeding introduced infectious disease to Mallorcan amphibians
September 2008. The deadly Chytrid fungus that is frog and toad populations all over the world was inadvertently introduced into Mallorca by a captive breeding programme that was reintroducing a rare species of toad into the wild, according to a new study published in the journal Current Biology.
The study, by researchers from Imperial College London, reveals that captive Mallorcan midwife toads released into the wild in 1991 were infected with the chytrid fungus Batrachochytrium dendrobatidis (Bd). Measures to screen the health of the toads did not pick up the fungus, because at the time it was not known to science.
Driving amphibian extinctions
The new study suggests that an endangered species of frog from South Africa, Xenopus gilli, which was housed in the same room as the Mallorcan midwife toads, was responsible for spreading the infection to them.
About Mallorcan midwife toads
Mallorcan midwife toads were known only from fossils and were thought to be extinct until 1978, when they were 'discovered', hiding in inaccessible gorges in the northern Mallorcan mountains.
The Mallorcan midwife toad is on the list of the 800 species most likely to go extinct in the near future unless they receive special protection. They are ranked 55 on a list of the 100 species most threatened with extinction according to the Zoological Society of London EDGE ratings.
Some toads unaffected
Danger of Chytrid fungus in captive breeding
As soon as Bd was discovered in the late 1990s, screening for the disease was incorporated into amphibian conservation plans. Zoos are now moving towards breeding threatened frogs in strictly quarantined, biosecure facilities in an effort to prevent the disease spreading in captivity.
The chytrid fungus has also been added to a list of diseases that need to be quarantined compiled by the World Organisation for Animal Health. It is hoped that these quarantine measures will help those involved in conservation efforts to stop Bd from spreading further, by controlling the international trade in infected animals.
Different strain from Mainland Europe
Bd infects amphibians' skin and is thought to interfere with their ability to absorb water. Over 257 amphibian species are known to be affected by Bd. Some species are very susceptible and die quickly while others, which are more resistant, are carriers of the pathogen.