1. Department of Infectious Diseases, Kyorin University School of Medicine, Mitaka, Tokyo, Japan
2. Research Center for Zoonosis Control, Hokkaido University, Sapporo, Japan
3. Department of Pediatrics, Sapporo Kosei General Hospital, Sapporo, Japan
4. Institute of Laboratory Animals, Graduate School of Medicine, Kyorin University, Mitaka, Tokyo, Japan