Blood samples show deadly frog fungus at work in the wild

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Blood samples show deadly frog fungus at work in the wild

The fungal infection that has killed a record number of amphibians worldwide leads to deadly dehydration in frogs in the wild, according to a new study by University of California, Berkeley and San Francisco State University researchers.

High levels of an aquatic fungus called Batrachochytrium dendrobatidis (Bd) disrupt fluid and electrolyte balance in wild frogs, the scientists say, severely depleting the frogs' sodium and potassium levels and causing cardiac arrest and death.

Their findings confirm what researchers have seen in carefully controlled lab experiments with the fungus, but SF State biologist Vance Vredenburg said the data from wild frogs provide a much better idea of how the disease progresses.

"The mode of death discovered in the lab seems to be what's actually happening in the field," he said, "and it's that understanding that is key to doing something about it in the future."

The study is published online by peer-reviewed journal PLoS ONE and funded through the joint National Science Foundation and National Institutes of Health program, Ecology and Evolution of Infectious Diseases.

At the heart of the new study are blood samples drawn from mountain yellow-legged frogs by Vredenburg, who is an assistant professor of biology at SF State, and colleagues in 2004, as the chytrid epidemic swept through the basins of the Sierra Nevada range.

"It's really rare to be able to study physiology in the wild like this, at the exact moment of a disease outbreak," said UC Berkeley ecologist Jamie Voyles, the lead author of the study.

At least it appears we know the cause of these extinctions and may be able to do something about it.