1. National Institute of Animal Health, National Agriculture and Food Research Organization, Tsukuba, Ibaraki, Japan
2. United Graduate School of Veterinary Sciences, Gifu University, Gifu, Gifu, Japan
3. Graduate School of Life and Environmental Sciences, Osaka Prefecture University, Izumisano, Osaka, Japan
4. Oita Livestock Hygiene Service Center of Oita Prefecture, Oita, Oita, Japan