1. Department of Wildlife Science, College of Bioresource Sciences, Nihon University, 1866 Kameino, Fujisawa, Kanagawa 252-8510, Japan
2. Department of Veterinary Microbiology, Gifu University, 1-1 Yanagito, Gifu 501-1112, Japan
3. Institute of Alpine Environmental Research, 12-388 Inao, Taira, Ohmachi, Nagano 398-0001, Japan