[1] Univ Oxford, Nuffield Dept Clin, Lab Sci, Oxford OX3 9BQ, England
[2] John Radcliffe Hosp, Natl Blood Serv, Oxford OX3 9BQ, England
[3] MRC Labs, Fajara, Gambia
[4] Kenya Govt Med Res Ctr, Ctr Geog Med Coast, Kilifi, Kenya
[5] Makerere Univ, Dept Pediat, Mulago Hosp, Kampala, Uganda
[6] UCL, Inst Child Hlth, Wolfson Ctr, Neurosci Unit, London WC1N 2AP, England