1. Naka-Sorachi Agricultural Mutual Aid Association, 1–5–14 Omachi, Takikawa 073–0022, Japan
2. Hokkaido Research Station, National Institute of Animal Health, 4 Hitsujigaoka, Toyohira, Sapporo 062–0045, Japan
3. Ishikari Livestock Hygiene Service Center, 3 Hitsujigaoka, Toyohira, Sapporo 062–0045, Japan
4. Tokachi Livestock Hygiene Service Center, 59–6 Kisen, Kawanishi, Obihiro 089–1182, Japan