[1] Gifu Prefectural Govt, Director Publ Hlth, Gifu 5008570, Japan
[2] Gifu Prefectural Govt, Med Treatment Div, Gifu 5008570, Japan
[3] Emory Univ, RSPH, HDGH, Atlanta, GA 30322 USA
[4] Juntendo Univ, Sch Med, Dept Publ Hlth, Tokyo 113, Japan
[5] ICDDR,B, Dhaka, Bangladesh
[6] CDC, Natl Ctr Immunizat & Resp Dis, Div Viral Dis, Atlanta, GA USA
[7] NIH, Fogarty Int Ctr, Bethesda, MD 20892 USA