1. Kamikawa Livestock Hygiene Service Center, 4–15 Higashitakasu, Asahikawa 071–8154, Japan
2. Ishikari Livestock Hygiene Service Center, 3 Hitsujigaoka, Toyohira, Sapporo 062–0045, Japan
3. Saroma Veterinary Clinical Center, Okhotsk Agricultural Mutual Relief Association, 127–2 Nishitomi, Saroma 093–0504, Japan
4. Hokkaido Research Station, National Institute of Animal Health, 4 Hitsujigaoka, Toyohira, Sapporo 062–0045, Japan