1. Department of Environmental Sciences, University of Virginia , Charlottesville, VA
2. Department of Public Health and Clinical Medicine, Umeå Center for Global Health Research, Umeå University , Umeå, Sweden
3. INDEPTH Network Secretariat , Accra, Ghana
4. School of Public Health, University of the Witwatersrand , Johannesburg, South Africa
5. Institute of Public Health, University of Heidelberg Medical School , Heidelberg, Germany