[1] London Sch Hyg & Trop Med, Dept Populat Hlth, Keppel St, London WC1E 7HT, England
[2] African Populat & Hlth Res Ctr, Nairobi, Kenya
[3] Ifakara Hlth Inst, Ifakara, Tanzania
[4] Univ Southampton, Dept Social Stat & Demog, Southampton, Hants, England
[5] Africa Ctr Populat Hlth, Mtubatuba, South Africa
[6] Manicaland Ctr Publ Hlth Res, Harare, Zimbabwe
[7] Malawi Epidemiol & Intervent Res Unit, Lilongwe, Malawi
[8] Kenya Govt Med Res Ctr, Kisumu, Kenya
[9] Ctr Dis Control, Kisumu, Kenya
[10] Uganda Virus Res Inst, Rakai Hlth Sci Program, Rakai, Uganda
[11] Tanzania Natl Inst Med Res, Tazama Project, Mwanza, Tanzania
[12] Univ Witwatersrand, Sch Publ Hlth, MRC Wits Rural Publ Hlth & Hlth Transit Res Unit, Johannesburg, South Africa
[13] MRC UVRI Uganda Res Unit AIDS, Entebbe, Uganda