[1] Univ Cape Town, Sch Publ Hlth & Family Med, Infect Dis Epidemiol Unit, ZA-7925 Cape Town, South Africa
[2] Columbia Univ, Mailman Sch Publ Hlth, Dept Epidemiol, New York, NY 10027 USA
[3] G F Jooste Hosp, HIV & Infect Dis Unit, Cape Town, South Africa
[4] Univ Cape Town, Dept Med, ZA-7700 Rondebosch, South Africa
[5] Univ Cape Town, Sch Publ Hlth & Family Med, Womens Hlth Res Unit, ZA-7700 Rondebosch, South Africa