Thursday, May 16, 2013

[Herpetology • 2013] Batrachochytrium dendrobatidis (Bd) Infection and Lethal Chytridiomycosis in Caecilian Amphibians (Gymnophiona)

This Cameroon caecilian species, Geotrypetes seraphini, tested positive for the fungus that can cause the deadly chytrid disease chytridiomycosis in frogs, toads, newts and salamanders.

Batrachochytrium dendrobatidis (Bd) is commonly termed the ‘amphibian chytrid fungus’ but thus far has been documented to be a pathogen of only batrachian amphibians (anurans and caudatans). It is not proven to infect the limbless, generally poorly known, and mostly soil-dwelling caecilians (Gymnophiona). We conducted the largest qPCR survey of Bd in caecilians to date, for more than 200 field-swabbed specimens from five countries in Africa and South America, representing nearly 20 species, 12 genera, and 8 families. Positive results were recovered for 58 specimens from Tanzania and Cameroon (4 families, 6 genera, 6+ species). Quantities of Bd were not exceptionally high, with genomic equivalent (GE) values of 0.052–17.339. In addition, we report the first evidence of lethal chytridiomycosis in caecilians. Mortality in captive (wild-caught, commercial pet trade) Geotrypetes seraphini was associated with GE scores similar to those we detected for field-swabbed, wild animals.

Keywords: Africa, Anura, Batrachia, Caudata, chytrid, pet trade, South America

Fatal fungus found in third major amphibian group, caecilians

It is known as the amphibian chytrid fungus and can cause a deadly disease that is decimating some of the world's frogs, toads, newts and salamanders. However, the fungus had not been detected in the other lesser-known major group of amphibians, the caecilians, until now.

An international team led by scientists at the Natural History Museum and Zoological Society of London (ZSL) have found the first cases of chytrid fungus infections in caecilians. They report their findings today in the journal EcoHealth.

More than 200 caecilians caught from the wild had DNA tests carried out on swabs of their skin to check for the amphibian chytrid fungus, Batrachochytrium dendrobatidis. The study included 29 caecilian species from 5 countries in Africa and South America, which is the largest genetic survey of this fungus in caecilians to date. 

2013. Batrachochytrium dendrobatidis Infection and Lethal Chytridiomycosis in Caecilian Amphibians (Gymnophiona). EcoHealth. DOI: 10.1007/s10393-013-0831-9