1. Center for Global Safe Water, Sanitation, and Hygiene, Hubert Department of Global Health, Rollins School of Public Health, Emory University, Atlanta, Georgia;
2. Mathematica Policy Research, Washington, District of Columbia;
3. Centre for Zoonoses and Environmental Microbiology, Centre for Infectious Disease Control, RIVM, Amsterdam, The Netherlands;
4. The Noguchi Memorial Institute for Medical Research of the University of Ghana, Accra, Ghana