[1] Nagasaki Univ, Sch Trop Med & Global Hlth, Dept Global Hlth, Nagasaki, Japan
[2] Nagasaki Univ, Grad Sch Biomed Sci, Nagasaki, Japan
[3] London Sch Hyg & Trop Med, Fac Epidemiol & Populat Hlth, Dept Infect Dis Epidemiol, London, England
[4] Kobe Univ, Grad Sch Hlth Sci, Dept Publ Hlth, Kobe, Japan
[5] Nagasaki Univ, Inst Trop Med, Dept Protozool, Nagasaki, Japan
[6] Natl Ctr Infect Dis, 16 Jalan Tan Tock Seng, Singapore 308442, Singapore