[1] Columbia Univ, New York State Psychiat Inst, HIV Ctr Clin & Behav Studies, New York, NY 10032 USA
[2] Community Based Publ Works Programme, Dept Publ Works, Pretoria, South Africa
[3] S African Med Res Council, Ctr Epidemiol Res, Durban, South Africa
[4] Columbia Univ, Joseph Mailman Sch Publ Hlth, Div Epidemiol, New York, NY USA