1. Fukushima Prefectural Chuou Livestock Hygiene Service Center, 114-12 Arayashiki, Ganpouji, Tamakawa, Ishikawa, Fukushima 963-6311, Japan
2. Chiba Prefectural Chuou Livestock Hygiene Service Office, 497 Iwatomimachi, Sakura, Chiba 285-0072, Japan
3. Sugadaira Research Station, Mountain Science Center, Faculty of Life and Environmental Sciences, University of Tsukuba, 1278-294 Sugadaira kogen, Ueda, Nagano 386-2204, Japan
4. Division of Zoonosis Research, National Institute of Animal Health, National Agriculture and Food Research Organization (NARO), 3-1-5 Kannondai, Tsukuba, Ibaraki 305-0856, Japan
5. Department of Veterinary Science, Graduate School of Life and Environmental Sciences, Osaka Prefecture University, 1-58 Rinku-oraikita, Izumisano, Osaka 598-8531, Japan