1. Department of Microbiology, Yamagata Prefectural Institute of Public Health, Yamagata, Japan
2. Yamanobe Paediatric Clinic, Yamagata, Japan
3. Department of Paediatrics, Yamagata Prefectural Central Hospital, Yamagata, Japan
4. Department of Neurology, Yamagata Prefectural Central Hospital, Yamagata, Japan
5. Department of Paediatrics, Tendo City Hospital, Yamagata, Japan
6. Department of Paediatrics, Okitama Public General Hospital, Yamagata, Japan
7. Department of Neurology, Yamagata University Faculty of Medicine, Yamagata, Japan
8. Department of Paediatrics, Yamagata City Hospital Saiseikan, Yamagata, Japan
9. Department of Infectious Diseases, Yamagata Prefectural Central Hospital, Yamagata, Japan