[1] Univ KwaZulu Natal, Africa Ctr Hlth & Populat Studies, Somkhele, South Africa
[2] Univ Southampton, Sch Social Sci, Southampton, Hants, England
[3] UCL Inst Child Hlth, Ctr Paediat Epidemiol & Biostat, London, England
[4] Uganda Virus Res Inst, MRC, Uganda Res Unit AIDS, Entebbe, Uganda
[5] London Sch Hyg & Trop Med, London WC1, England
[6] Univ E Anglia, Sch Int Dev, Norwich NR4 7TJ, Norfolk, England
[7] WHO, Multicountry Studies Unit, CH-1211 Geneva, Switzerland
[8] Univ Newcastle, Res Ctr Gender Hlth & Ageing, Newcastle, NSW 2300, Australia