1. Department of Microbiology and Oncology, Graduate School of Medicine, University of the Ryukyus, 207 Uehara, Nishihara, Okinawa 903-0215, Japan
2. Department of Pediatrics, Mahosot Hospital, Mahosot Road, 01030 Vientiane, Laos
3. Department of Pediatrics, Setthathirath Hospital, Boulevard Kamphengmeuang, 01030 Vientiane, Laos
4. Department of Communicable Disease Control, Ministry of Health, Si Mouang Road, 01030 Vientiane, Laos
5. Shimane Environment & Health Public Corporation, 1-4-6, Koshihara, Matsue, Shimane 690-0012, Japan