Deadly Amphibian Fungus May Emerge In Asia, Study

AsianScientist (Aug. 19, 2011) – Chytridiomycosis, caused by the fungus, Batrahochytrium dendrobatidis or Bd, has driven more than 200 species of amphibians in the Americas, Europe, and Australia to extinction.

In the journal PLoS One, a collaborative team of scientists has published the first major survey of the fungus in Asia. They found that the prevalence of Bd is very low in the continent, with only 2.35 percent of the surveyed animals being infected.

The Philippines, Kyrgyzstan, Laos, Indonesia, Malaysia and South Korea were the only countries with Bd infection and the animals were not clumped in a region, as would be anticipated in an epizootic event.

The team suggests that Bd is either newly emerging in Asia, endemic at low prevalence, or that some other ecological factor is preventing Bd from fully invading Asian amphibians.

Vance Vredenburg, assistant professor of biology at San Francisco State University, explains:

“Each site in the study was only surveyed once so it’s difficult to determine whether Bd infections in the countries are newly expanding.”

“It will be critical, to see how Bd prevalence is changing through time, because this is key to understanding the ultimate outcome of the disease,” he added.

The hypothesis that Bd has been in Asia for a long time raises the question why amphibians there have managed to co-exist with a fungus that has proved so destructive elsewhere. It is possible, for instance, that Asian amphibians might bear some sort of bacterial protection against Bd in their skins.

Scientists are analyzing the genes of the Bd fungus collected globally to find out whether strains from different parts of the world differ in virulence, said Vredenburg.

Vredenburg and colleagues state that if Asia is on the brink of a chytrid epizootic, it might start in the Philippines.

“The prevalence and intensity of Bd infection is much higher in the Philippines than anywhere else in Asia. Bd in the Philippines today looks similar to Bd in early outbreaks in California and South and Central America,” he cautioned.

The article can be found at: Swei A et al. (2011) Is Chytridiomycosis an Emerging Infectious Disease in Asia?

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Source: San Francisco State University; Photo: R. Brown, University of Kansas.
Disclaimer: This article does not necessarily reflect the views of AsianScientist or its staff.