North American frog is disease carrier

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SAN FRANCISCO, March 13 (UPI) -- Researchers say a common North American frog has been identified as a carrier of a deadly disease decimating world amphibian populations.

Finding how the Pacific chorus frog, known for its noisy and distinctive "ribbit" call, survives while carrying chytridiomycosis, a deadly disease caused by an aquatic fungus, may yield clues to protect more vulnerable species, scientists at San Francisco State University said Tuesday.

Their surveys in the Sierra Nevada revealed that between 2003 and 2010 Pacific chorus frog populations remained stable while during the same time period a chytrid epidemic swept through the region causing mass die-offs among other species.

Pacific chorus frogs survived the outbreak but did not escape infection, as investigation confirmed that two-thirds of the animals tested were infected with the fungus.

"The Pacific chorus frog is a perfect host for chytrid, allowing the disease to leap frog to the next pond over," SFSU biologist Vance Vredenburg said. "The findings help explain the pattern and speed of the chytrid epidemic in the Sierras."

The species rarely shows symptoms, researcher found, making it a highly effective carrier.

"We found that the vast majority of Pacific chorus frogs don't die or show symptoms even with surprisingly high levels of infection," researcher Natalie Reeders said. "They are able to go about life as normal, moving over land and carrying the disease to new locations."