1. Department of Infectious Disease, Tokyo Metro Tama Medical Center, 2-8-29 Musashidai, Fuchu, Tokyo 183-8524, Japan
2. Emergency & Trauma Center, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba 296-8602, Japan
3. Department of General Internal Medicine, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba 296-8602, Japan
4. Department of Infectious Disease, Kameda Medical Center, 929 Higashi-cho, Kamogawa, Chiba 296-8602, Japan
5. Department of Clinical Medicine, Institute of Tropical Medicine, Nagasaki University, 1-14 Bunkyo-cho, Nagasaki 852-8521, Japan
6. Department of General Internal Medicine, Eastern Chiba Medical Center, 3-6-2 Okayamadai, Togane, Chiba 283-8686, Japan
7. Department of General Medical Science, Graduate School of Medicine, Chiba University, 1-8-1 Inohana, Chuo-ku, Chiba 260-8670, Japan
8. Research & Development Center for Health Services, Faculty of Medicine, University of Tsukuba, 1-1-1 Tenno-dai, Tsukuba, Ibaraki 305-8575, Japan