1. MRC/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. INDEPTH Network Accra, Ghana
3. Umeå Centre for Global Health Research, Division of Epidemiology and Global Health, Department of Public Health and Clinical Medicine, Umeå University, Umeå, Sweden