1. Department of Environmental and Occupational Health, School of Public Health, Indiana University, Bloomington, Indiana47401, United States
2. Department of Environmental Sciences and Engineering, Gillings School of Public Health, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina27599, United States
3. Department of Disease Control, London School of Hygiene and Tropical Medicine, LondonWC1E 7HT, U.K.
4. Department of Biology, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina27599, United States
5. Department of Civil and Environmental Engineering, Georgia Institute of Technology, Atlanta, Georgia30332, United States
6. Ministério da Saúde, Instituto Nacional de Saúde Maputo, Maputo1102, Mozambique