1. Department of Microbiology; Yamagata Prefectural Institute of Public Health; 1-6-6 Toka-machi, Yamagata-shi, Yamagata 990-0031
2. Department of Public Health; Yamagata University Graduate School of Medicine; 2-2-2 Iida Nishi, Yamagata-shi, Yamagata 990-9585
3. Division of Collaboration and Education; Research Center for Zoonosis Control, Hokkaido University; Kita 20, Nishi 10, Kita-ku, Sapporo, Hokkaido 001-0020; Japan