1. Department of Bacteriology and Pathology; Kanagawa Prefectural Public Health Laboratories; Yokohama Kanagawa 241-0815 Japan
2. Sapporo Tetsudo Hospital; Sapporo Hokkaido 060-0033 Japan
3. Health Sciences University of Hokkaido; Sapporo Hokkaido 002-8072 Japan
4. Izumikawa Hospital; Nagasaki 859-1504 Japan
5. Hokkaido Children's Hospital and Medical Center; Otaru Hokkaido 047-0261 Japan
6. National Institute of Infectious Diseases; Musashimurayama Tokyo 208-0011 Japan