1. Faculty of Veterinary Medicine, Okayama University of Science, Ehime, Japan
2. Toyo Livestock Hygiene Service Center Imabari Branch Office in Ehime, Ehime, Japan
3. Equine Research Institute, Japan Racing Association, Tochigi, Japan
4. Department of Medical Entomology, National Institute of Infectious Diseases, Tokyo, Japan
5. Department of Veterinary Science, National Institute of Infectious Diseases, Tokyo, Japan