• Kyodo News


Thousands of frogs were found dead in a pond last fall in Japan’s first confirmed case of the amphibian-destroying ranavirus, a researcher said Friday.

The death of American Bullfrogs occurred in a man-made pond in September and October, said Yumi Une, associate professor of veterinary science at Azabu University in Kanagawa Prefecture.

The dead frogs had symptoms unique to a ranavirus infection, such as bleeding on the surface of the skin and loss or deformity of toes or webs, Une said, adding that the virus was detected in their cells.

Une did not reveal the location of the pond but said more than 10,000 frogs are believed to have died there.

Although the virus is not contagious to humans, no cure has been found for infected amphibian species.

The ranavirus, as well as the chytrid fungus, is thought to be one of the major causes of a recent global plunge in amphibian populations. The virus is killing off several amphibian species in Britain and the United States.

Une said the virus did not affect fish in the pond and that she is now conducting experiments to see if other amphibian species have been infected.

A new type of ranavirus was found in American Frogs in Taiwan last year, and a gene in the virus found in the dead frogs in Japan resembles one from the virus in Taiwan, Une said.

“Please contact veterinarians if you find a large number of frogs or other amphibians dead anywhere,” Une said.

The first case of an amphibian chytrid fungus infection was confirmed in Japan in 2006.

The fungus has been detected in American Frogs, Giant Salamanders and other amphibian species, but mass deaths have not been confirmed and it is possible the chytrid fungus found in Japan may be harmless.

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