1. Medical Research Council/Wits Rural Public Health and Health Transitions Research Unit (Agincourt), School of Public Health, Faculty of Health Sciences, University of the Witwatersrand , Johannesburg, South Africa
2. Department of Science and Innovation/Medical Research Council, South African Population Research Infrastructure Network , Durban, South Africa
3. Population Studies and Training Center, Brown University , Providence, RI, USA
4. Department of Urban Public Health, University of Massachusetts , Boston, MA, USA
5. Department of Epidemiology and International Health Institute, School of Public Health, Brown University , Providence, RI, USA
6. Department of Anthropology, Brown University , Providence, RI, USA
7. Department of Public Health, University of Missouri , Columbia, MO, USA