[1] Univ London London Sch Hyg & Trop Med, MRC, Trop Epidemiol Grp, Dept Infect & Trop Dis, London WC1E 7HT, England
[2] Mahidol Univ, Dept Dermatol, Sexually Transmitted Infect Clin, Bangkok 10700, Thailand
[3] Univ Sherbrooke, Ctr Int Hlth, Sherbrooke, PQ J1K 2R1, Canada
[4] UCL, Ctr Sexual Hlth & HIV Res, London, England
[5] Mahidol Univ, Dept Microbiol, Bangkok 10400, Thailand
[6] GlaxoSmithKline, Worldwide Epidemiol, Greenford, Middx, England
[7] Mahidol Univ, Dept Obstet & Gynaecol, Bangkok 10700, Thailand
[8] Med Res Council Programme AIDS Uganda, Entebbe, Uganda