Amphibian Disease Linked to Wildlife Trade

Nov 17, 2011 | Amy L. Sonricker Hansen | Outbreak News

Recent research published in the journal of the Proceedings of the National Academy of Sciences of the United States (PNAS) has shown that the chytrid fungus (chytridiomycosis), which has wiped out dozens of species of amphibians worldwide, was likely spread via the wildlife trade. Scientists from the Imperial College of London sequenced the genomes of 20 samples of fungus collected from 11 species from across the globe, and found that 16 of the 20 had a genetically identical type of Batrachochytrium dendrobatidis fungus (BdGPL). Two other distinct lineages of the fungus were identified, however the BdGPL was the most common and also the most deadly. Genetic recombination (a process in which genes are broken down and shuffled to produce new genes) was determined to be the most likely explanation for the genome differences, and that means that it could occur again creating even more virulent strains.

With scientists now able to assess that the fungus arose in the 20th century, it was then clear that the fungus likely spread by way of the global trade in amphibians. The start of the 20th century coincides with the start of the global amphibian trade, and in the early 1970s the global decline of amphibians began. The trade in frogs and other amphibians continues to involve both the legal and illegal trade of amphibians around the world for exhibition in zoos, for use in research and as part of the exotic pet trade. Based on the findings from this research, scientists are calling for a global quarantine of imported amphibians to aid in slowing the progress of chytrid fungus, and to block new strains from being introduced. There are still countries where BdGPL has not yet penetrated, and where diverse populations of amphibians exist that would be decimated if exposed to the fungus. Southeast Asia and Madagascar are two regions in most urgent need of protection according to one of the study’s authors.

The chytrid fungus infects amphibians through the skin leading to cardiac arrest or suffocation, and is suspected in the extinction of over 200 species of amphibians worldwide. Research on the deadly BdGPL fungus is ongoing, and this latest study provides a new direction of hope in that perhaps the less lethal strains of the fungus may be used to provide some type of immunity in amphibians not yet affected.  

 

Organizations working to ensure the global survival of remaining amphibian species:

Amphibian Ark

World Association for Zoos and Aquariums

 

Journal reference: Proceedings of the National Academy of Sciences, DOI: 10.1073/pnas.1111915108

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