[1] Univ Southampton, MRC Lifecourse Epidemiol Ctr, Southampton, England
[2] Biomed Res & Training Inst, Hlth Res Unit Zimbabwe, 10 Seagrave Rd, Avondale, Zimbabwe
[3] Univ Zimbabwe, Dept Med Phys & Imaging Sci, FMHS, Harare, Zimbabwe
[4] Univ Bristol, Bristol Med Sch, Musculoskeletal Res Unit, Bristol, England
[5] Univ Witwatersrand, Sch Clin Med, Dept Paediat, SAMRC Wits Dev Pathways Hlth Res Unit, Johannesburg, South Africa
[6] London Sch Hyg & Trop Med, Dept Infect Dis Epidemiol, Fac Epidemiol & Populat Hlth, London, England
[7] Univ Sheffield, Div Clin Med, Sheffield, England
[8] London Sch Hyg & Trop Med, Fac Infect & Trop Dis, Clin Res Dept, London, England
[9] London Sch Hyg & Trop Med, Fac Epidemiol & Populat Hlth, Dept Infect Dis Epidemiol, MRC Int Stat & Epidemiol Grp, London, England
[10] MRC Unit London Sch Hyg & Trop Med, Banjul, Gambia