1. Tochigi Prefectural Institute of Public Health, Utsunomiya-shi, Tochigi 329-1196, Japan
2. Yamaguchi Prefectural Institute of Public Health and Environment, Yamaguchi-shi, Yamaguchi 753-082, Japan
3. Gunma Prefectural Institute of Public Health and Environmental Sciences, Maebashi-shi, Gunma 371-0052, Japan
4. Department of Molecular Biodefence Research, Yokohama City University Graduate School of Medicine, Yokohama-shi, Kanagawa 236-0004, Japan
5. Yamagata Prefectural Institute of Public Health, Yamagata-shi, Yamagata 990-0031, Japan
6. Department of Pediatrics, Yamaguchi University Graduate School of Medicine, Ube-shi, Yamaguchi 755-8505, Japan
7. Department of Surgery, Kyorin University, School of Medicine, Mitaka-shi, Tokyo 181-8611, Japan
8. Department of Nutritional Science, Tokyo Kasei University, Itabashi-ku, Tokyo 173-8602, Japan
9. Department of Virology III, National Institute of Infectious Diseases, Musashimurayama-shi, Tokyo 208-0011, Japan
10. Infectious Disease Surveillance Center, National Institute of Infectious Diseases, Musashimurayama-shi, Tokyo 208-0011, Japan