Secrets of a deadly frog disease

	The skin fungus that has laid waste to amphibian populations around the world does its damage by hindering the flow of sodium and other electrolytes across the skin, leading to... Click here for more information.

The skin fungus that has laid waste to amphibian populations around the world does its damage by hindering the flow of sodium and other electrolytes across the skin, leading to heart failure, according to new research in the October 23 issue of Science. These findings may offer a foundation for developing new methods to save endangered populations in the future. The skin disease chytridiomycosis, caused by the fungus Batrachochytrium dendrobatidis, is believed to be one of the major causes of the global amphibian declines that have been underway in recent years. But, how the fungus actually kills its victims has been a mystery, since the dead animals generally appear healthy and don't show other signs of disease other than skin lesions. Jamie Voyles and colleagues report that in green tree frogs infected with the fungus, transport of electrolytes across the skin was inhibited by more than 50 percent, and sodium and potassium concentrations in the frogs' plasma were reduced by 20 and 50 percent, respectively. Cardiac electrograms revealed that the dying frogs' hearts were slowing and eventually stopping altogether, most likely due to electrolyte imbalance. Supporting this idea, the authors found that diseased frogs fed an electrolyte supplement lived longer than those without it, although they ultimately succumbed to the infection. More research will be necessary to show exactly how the fungus disrupts the animals' osmotic balance across the skin.

Article #13: "Pathogenesis of Chytridiomycosis, a Cause of Catastrophic Amphibian Declines," by J. Voyles; S. Young; L. Berger; R. Webb; R.A. Alford; L.F. Skerratt; R. Speare at James Cook University in Townsville, QLD, Australia; C. Campbell; A. Dinudom; D. Cook at University of Sydney in Sydney, NSW, Australia; W.F. Voyles at University of New Mexico in Albuquerque, NM.

Contact: Jamie Voyles at +61-413-156-592 (phone), or jamie.voyles@gmail.com (email). Dr. Voyles is available for interviews in English and Spanish.