[1] McCord Hosp, ZA-4067 Durban, South Africa
[2] Univ KwaZulu Natal, Nelson Mandela Sch Med, Infect Dis Unit, Durban, South Africa
[3] Harvard Univ, Harvard Sch Publ Hlth, Ctr Biostat AIDS Res, Boston, MA 02115 USA
[4] Univ Cape Town, Sch Med, ZA-7925 Cape Town, South Africa
[5] Univ So Calif, Sch Med, Los Angeles, CA USA