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Scientists uncover mystery of how frog plague kills its victims

One hundred and twenty species of frogs are reported to have gone extinct since 1980 (although the number is likely even higher). While devastated by habitat loss, pollution, and climate change, a baffling disease may be the biggest factor behind the alarming extinctions of frogs. Called chytridiomycosis, the disease is caused by the microscopic fungus Batrachochytrium dendrobatidis which kills its tiny victims indiscriminately.

First discovered in 1998, chytridiomycosis has left scientists baffled as to how it kills frogs, which in turn leaves them guessing as to how to stop the plague. However, the quest to halt chytridiomycosis in its tracks has received a boost this week. A new study in Science is the first to identify how the disease attacks and kills frogs, bringing scientists one step closer to a cure.

The endangered corroboree frog with chytridiomycosis, a lethal skin disease of
amphibians. Image courtesy of Jamie Voyles, Alex Hyatt and Frank Fillipi.

Jaime Voyles, a graduate student in disease ecology at James Cook University, Townsville, in Australia, has found that chytridiomycosis hinders the flow of sodium and other electrolytes across the frog’s skin, eventually causing heart failure.

By studying green tree frogs with the disease Voyles and her colleagues were able to see the electrolyte transport across the skin was hindered by over 50 percent, while sodium was reduced by 20 percent and potassium, 50 percent.

To test that it was in fact electrolytes that was causing the heart failure, Voyles and her team gave an electrolyte supplement to a portion of the frogs. Individuals given the supplement were able to move slightly and survived 20 hours longer than the infected frogs lacking the supplement.

The research team says that future studies should look into how the disease disrupts the frogs’ osmoregualtion, which is the mechanism that ensures the individual’s electrolytes remain balanced.

Citation: Jamie Voyles, Sam Young, Lee Berger, Craig Campbell, Wyatt F. Voyles, Anuwat Dinudom, David Cook, Rebecca Webb, Ross A. Alford, Lee F. Skerratt, Rick Speare. “Pathogenesis of Chytridiomycosis, a Cause of Catastrophic Amphibian Declines”. Science. Vol 326. October 23 2009.

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