January and February of 2004, three outbreaks of HPAI caused by H5N1 virus occurred in Japan since 1925. The first outbreak occurred in a layer farm located on the mountains, Yamaguchi prefecture, western Japan. About 14,600 of 34,600 laying hens reared in this farm died between 28th December 2003 and 14th January 2004. The second outbreak occurred in the bantams reared in a family as pet birds. In this case, 14 birds died. The third outbreak occurred in a layer farm reared about 260,000 chickens. Since owner of this farm did not report this outbreak to local government, this case became a serious disaster. It is still obscure how causative virus was carried to Kyoto prefecture.
Keywords: highly pathogenic avian influenza, H5N1, Yamaguchi, Kyoto, layer