[1] Kenya Govt Med Res Ctr, Wellcome Trust Res Programme, Malaria Publ Hlth Grp, Nairobi, Kenya
[2] Minist Publ Hlth & Sanitat, Div Malaria Control, Nairobi, Kenya
[3] Pharm & Poisons Board, Nairobi, Kenya
[4] Univ London London Sch Hyg & Trop Med, London WC1E 7HT, England
[5] Univ Oxford, Nuffield Dept Clin Med, Ctr Trop Med, Oxford, England