[1] Swiss Trop Inst, Dept Publ Hlth & Epidemiol, CH-4002 Basel, Switzerland
[2] KEMRI Wellcome Trust Collaborat Programme, Nairobi 00100, Kenya
[3] KEMRI Ctr Geog Med Res Coast, Kilifi, Kenya
[4] Univ Oxford, Nuffield Dept Clin Med, Ctr Trop Med, Oxford, England
[5] Univ Oxford, Dept Paediat, Oxford, England
[6] Oxford Radcliffe Hosp Trust, Oxford, England