VIENNA - An Austrian cat which has twice tested positive for the H5N1 bird flu virus did not show the virus in a third probe today, Austria's health ministry said, adding to uncertainty about the infection in cats.
The cat is one of 170 that were kept in an animal sanctuary in southern Austria close to a cage of fowl which had been infected with H5N1. Three cats tested positive for the virus in saliva tests last week, Austria said yesterday.
A subsequent test of the three cats' faeces confirmed H5N1 in only one of the samples, in a very low concentration. A third faeces test taken today was negative for all of them, a health ministry spokeswoman said.
However, the spokeswoman added the ministry was still waiting for the results of tests on the cats' blood.
"Apparently cats are more resistant than chicken," the spokeswoman said. "That you find the virus in the mouth apparently doesn't mean that it reaches the other end too."
The 170 cats, 40 of which had been saliva-tested in the Noah's Ark sanctuary in the city of Graz, were brought to a quarantine centre close to Vienna for observation and tests.
The World Health Organisation (WHO) said today that more studies were needed on infections in cats, including how they shed the virus in their environment.
The WHO asked Austria to provide more detail on the cats, adding that it was potentially significant if an animal could contract the virus and not show any symptoms of illness.
Johann Thalhammer, a professor at Vienna's veterinary university who is now monitoring the cats, said he could not confirm that they did not have any symptoms of the virus.
"There were no symptoms that the people in the sanctuary noticed," Thalhammer said. "How exactly they were observing the cats in the sanctuary I don't know."
"What we are looking for now is: are there more cats testing positive? Are those which are infected showing any symptoms that can be correlated to the virus?," he added.
Bird flu can wipe out poultry flocks in the space of 48 hours and can also infect people who come into close contact with infected birds. It has killed at least 95 people in Asia and the Middle East since late 2003.