Zoo koalas carry virus linked to leukemia

Nearly 90 per cent of the koalas in Japanese zoos are infected with a retrovirus believed to cause leukemia and lymphoma.

Researchers at the Institute for Virus Research at Kyoto University and the Japanese Association of Zoos and Aquariums tested the blood of 50 of the 62 koalas kept in Japan, the daily Yomiuri said.

It is thought most likely the koalas already were infected before being imported from Australia.