The highly pathogenic H5 strain was detected in ducks found dead at a farm in Aomori Prefecture, northern Honshu, on 28 November, while, some 450km away in Niigata Prefecture, western Honshu, dead chickens at a poultry farm tested positive at two separate sites on 28 and 30 November.
To stem the disease, local governments have destroyed about 560,000 chickens and ducks, and introduced quarantine measures. Producers within 10km of the farms have been banned from transporting their poultry and eggs, affecting about 65 farms, accounting for nearly 1 million birds.
The Japanese government said it would continue to take steps to prevent the infections from spreading and keep the public informed.
This strain is the first found in domestic poultry in Japan since January 2015. However, four cases of the same strain have been confirmed in South Korea in recent weeks, according to South Korea’s Ministry of Food, Agriculture and Rural Affairs, prompting suspicion that the virus has crossed borders.
“The H5N6 strain [in Japan] is the same as the one in South Korea, suggesting it came into Japan naturally through the movements of wild birds,” said a representative of the Japan Chicken Association. Adding to the concern, Japan’s Ministry of the Environment announced, on 18 November, that the strain was also found in nesting watercourses in Izumi City, Kagoshima Prefecture, in the southern island of Kyushu, within the country’s largest migration ground for cranes.
The Japan Chicken Association hoped the government’s prompt response would prevent the outbreak causing major commercial damage nationwide: “If the virus can be contained, there will not be a great impact on the industry. And during the outbreak two years ago, the local and national governments were successful in stopping it,” the representative recalled.
A spokesperson for Japan’s National Institute of Animal Health said control measures in Niigata and Aomori had been “well performed” and the affected areas would be back to normal a few months after control measures are completed, provided there “are not successive outbreaks in the area”.
He was less optimistic about the impact on the industry: “As the affected area in Aomori is not densely populated with poultry, the risk to nearby poultry would be limited. But there are not so many farms that rear ducks for foie gras in Japan, so the outbreak there could damage domestic production.”
Meanwhile, the halt to egg production at the affected farms in Niigata could have a significant economic impact, the spokesperson explained.