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