[1] Univ London London Sch Econ & Polit Sci, LSE Hlth, London WC2A 2AE, England
[2] Natl Inst Malariol Parasitol & Entomol, Hanoi, Vietnam
[3] Inst Trop Med Prince Leopold, B-2000 Antwerp, Belgium
[4] Ninh Thuan Prov Ctr Malariol Parasitol & Entomol, Phan Rang, Vietnam
[5] Univ London London Sch Hyg & Trop Med, London WC1E 7HT, England