1. Department of Environmental Sciences and Engineering, UNC Gillings School of Global Public Health, Chapel Hill, North Carolina, USA
2. Department of Environmental Health and Engineering, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA
3. Microbiology and Infection Control, Statens Serum Institute, Copenhagen, Denmark
4. Rural Empowerment Association for Community Help, Warsaw, North Carolina, USA
5. Johns Hopkins University School of Medicine, Baltimore, Maryland, USA
6. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland, USA