1. a Department of Environmental Health, College of Medicine and Health Sciences, University of Rwanda, P.O. Box 3286, Kigali, Rwanda
2. b Department of Disease Control and Environmental Health, School of Public Health, College of Health Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda
3. c Department of Community Health and Behavioural Sciences, School of Public Health, College of Health Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda
4. d Department of Epidemiology and Biostatistics, School of Public Health, College of Health Sciences, Makerere University, P.O. Box 7072, Kampala, Uganda