1. Kagoshima Research Station, National Institute of Animal Health, National Agriculture and Food Research Organization, Kagoshima, Japan.
2. Okinawa Prefectural Institute of Animal Health, Uruma, Japan.
3. Yaeyama Livestock Hygiene Service Center, Ishigaki, Japan.
4. Department of Medical Entomology, National Institute of Infectious Diseases, Shinjuku, Japan.