bird flu in China
© AP
Chiba Prefecture announced Thursday an outbreak of avian influenza believed to be highly pathogenic at a chicken farm in the city of Isumi in the eastern Japan prefecture.

Since November, farm outbreaks of such bird flu have occurred in 12 prefectures, including the western prefecture of Kagawa and the southwestern prefecture of Miyazaki. Chiba is the 13th prefecture to report an outbreak this year and the first to do so in eastern Japan.

Chiba has the second-largest number of farmed egg-laying hens in the country, after Ibaraki Prefecture, also in eastern Japan.

The affected poultry farm is one of the largest of its kind in the nation.

To stem the spread of the infection, the Chiba prefectural government will cull all of some 1.16 million chickens at the farm, the biggest number ever in a single bird flu outbreak case in Japan.