1. Department of Microbiology, Yamagata Prefectural Institute of Public Health, Yamagata, Japan
2. Department of Infectious Diseases, Yamagata University School of Medicine, Yamagata, Japan
3. Yamanobe Pediatric Clinic, Yamagata, Japan
4. Sanjoh Clinic, Yamagata, Japan
5. Department of Pediatrics, Yamagata City Hospital, Saiseikan, Yamagata, Japan