1. Division of Bacterial and Parasitic Disease, National Institute of Animal Health, National Agriculture and Food Research Organization, 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan
2. Tottori Station, National Livestock Breeding Center, 14 Idekami, Kotoura, Tohaku, Tottori 689-2511, Japan
3. Niigata Chuo Livestock Hygiene Service Center, 686 Hataya, Nishikan-ku, Niigata 959-0423, Japan
4. Kumamoto Chuo Livestock Hygiene Service Center, 1666-1 Jonanmachi, Shizume, Minami-ku, Kumamoto 861-4215, Japan