The genes of Japan’s avian flu virus are almost identical to those of South Korea’s, the farm ministry said Friday.
The results of tests carried out by the ministry appear to support speculation that migratory birds from South Korea carried the virus to Japan.
But government officials and experts said there is still insufficient information to confirm that migratory birds were the vehicles of infection.
According to the Agriculture, Forestry and Fisheries Ministry, tests undertaken by the National Institute of Animal Health showed that the genes of the virus found in Yamaguchi, Oita and Kyoto prefectures are “more than 99 percent” identical to those of the virus found in South Korea, where poultry farms were hit by the flu from December to February.
Farm minister Yoshiyuki Kamei said the test results alone have not led him to conclude that the virus responsible for the outbreak in Japan came from South Korea.
Environment Minister Yuriko Koike agreed.
“We have not reached a conclusion that all the problems (of bird flu in Japan) are attributable to migratory birds,” Koike told a news conference. “We want to conduct a thorough investigation (into the route of the infection) by gathering information and analysis.”
The Environment Ministry dispatched officials to South Korea last week. They were told by South Korean authorities that no wild birds infected with the virus have been found since the outbreak in December.
Farm ministry officials said the ministry plans to inspect the genes of the flu virus found in China, where an outbreak came to light in January.
According to Katsuya Hirai, a professor emeritus at Gifu University and an expert in veterinary medicine, the virus found in Japan probably came from South Korea.
Yutaka Kanai, a researcher at the Wild Bird Society of Japan and a member of the Environment Ministry’s advisory group on the bird flu issue, also pointed to a South Korea connection, not just because of the test results but also due to Japan’s proximity to the country.
“But the problem is what carried the virus (to Japan)'” Kanai asked. No data have emerged to pinpoint migratory birds as the virus carriers, he said, adding that humans could also have been the vehicle.
The Environment Ministry has been researching wild birds in areas around flu-outbreak sites in Yamaguchi, Oita, and Kyoto prefectures, but no evidence has been found to connect migratory birds with the outbreak.
In Yamaguchi, 91 wild birds of 17 varieties, including migratory birds of six varieties, were captured and their droppings and blood were inspected at Tottori University.
Test results unveiled last week show that none of the examined birds had been infected.
Droppings and blood of wild birds from Oita and Kyoto are still under inspection, according to the ministry.
Crows in the Kansai region, however, did test positive for the virus.
Kanai of the wild bird society said that more than 100 kinds of birds migrate from South Korea to Japan.
In winter, migratory birds on the Korean Peninsula and other parts of Asia fly to Japan, which is warmer, he explained.
Toshihiro Ito, a professor at Tottori University and an expert in veterinary medicine, said the virus could have been carried by migratory birds into the three areas via different routes.
“It is less likely that the virus multiplied in Yamaguchi and Oita, and moved to Kyoto, as the spread of the disease at the two sites had been contained before the flu outbreak in Kyoto,” said Ito, who is a member of the ministry’s advisory group.
Kanai said it is unlikely that wild birds carried the virus directly from Yamaguchi to Oita and Kyoto.