[1] Mahidol Univ, Fac Trop Med, Dept Clin Trop Med, Bangkok 10400, Thailand
[2] Mahidol Univ, Fac Trop Med, Bangkok Sch Trop Med, Bangkok 10400, Thailand
[3] Mahidol Univ, Fac Trop Med, Dept Trop Hyg, Bangkok 10400, Thailand
[4] Mahidol Univ, Fac Trop Med, Hosp Trop Dis, Bangkok 10400, Thailand
[5] Int Med Ctr Japan, Minist Hlth Labour & Welfare Japan, Res Inst, Dept Appropriate Technol Dev & Transfer, Tokyo, Japan