1. Department of Microbiology, Yamagata Prefectural Institute of Public Health, Japan
2. Yamanobe Pediatric Clinic, Japan
3. Katsushima Pediatric Clinic, Japan
4. Department of Infectious Diseases, Yamagata University Faculty of Medicine, Japan
5. Department of Virology III, National Institute of Infectious Diseases, Japan
6. Infectious Diseases Surveillance Center, National Institute of Infectious Diseases, Japan