Japan Hit By Bird Flu Strain

A bird flu virus that had infected pet chickens in southern Japan has been confirmed as the same deadly strain that has ravaged other parts of Asia, a researcher at a government research center said Thursday.

The World Health Organization listed Japan among the countries affected by the avian flu after an outbreak last month killed thousands of egg laying chickens in the country's southwest. Until now, however, Japan did not acknowledge having the H5N1 virus.

Health experts say migratory birds, fighting cocks and farmers' trucks could be behind bird flu's persistent spread through Asia despite massive culls.

None of the eight Asian countries struck by the deadlier strain of avian influenza that has decimated poultry and killed 22 people have managed to control their outbreaks despite intense efforts by many of them, the World Health Organization said.

More than 80 million chickens and other fowl have been slaughtered to contain the disease.

Masataka Tangiku, head of virus research at Japan's National Institute of Animal Health in Tsukuba city, north of Tokyo, said tests on tissue from the seven pet chickens tested positive for the virus.

The chickens died between Saturday and Monday at a home in the town of Kokonoe in Oita Prefecture (state), about 530 miles southwest of Tokyo. Earlier tests had failed to identify the virus, though Japanese researchers suspected it to be an H5 strain.

Tangiku said scientists haven't been able to trace how the virus reached pet birds kept at an ordinary household.

Avian flu generally infects only birds, although it has spread to people in a few isolated cases. The virus has only jumped to humans in Thailand — where it has killed seven people — and Vietnam, where 15 people have died.

Also affected by the H5N1 strain are Cambodia, Indonesia, Laos and South Korea. Pakistan and Taiwan are reporting a milder strain of the virus.

Past outbreaks of the H5N1 strain — which killed six people in Hong Kong in 1997 — have taken years to bring under control, and never has the disease spread as far and as fast as it has this year.

Although most of the human cases have been traced to direct contact with sick birds, experts fear that the longer it takes to contain the virus, the greater the chances are that it might link with the human flu virus and become easily transmittable from person to person, sparking a new flu pandemic.

Japan's outbreak last month killed thousands of chickens at a farm in Yamaguchi prefecture, the country's first case of bird flu in 79 years. No link between the Oita and Yamaguchi outbreaks has been found.

On Thursday, Thai officials launched a probe into the deaths in early February of 196 cows and buffalos in the country's northeast. Samples of manure from the animals, who were eaten by local residents, were being collected for testing.

Thai authorities have confirmed that a rare clouded leopard at a zoo had died from the illness after eating raw chicken. A Thai-language newspaper reported Thursday on its Web site that a veterinary hospital has detected the bird flu virus in a pet cat, which had eaten dead chickens.

The U.N. agency cited ways the bird flu may be spreading despite the culls: prized fighting cocks hidden by their owners, migratory birds who carry the virus but are not sickened by it and contaminated farming vehicles.

"Countries need to maintain a high level of vigilance, and must not relax their surveillance and detection efforts," WHO said in a report posted Thursday in Asia. "Complete elimination of the virus is becoming increasingly challenging."