1. Rakai Health Sciences Program, P.O. Box 279, Kalisizo, Rakai, Uganda
2. Department of Community Health and Behavioral Sciences, Makerere University School of Public Health, P.O. Box 7072, Kampala, Uganda
3. Department of Medicine, Makerere University College of Health Sciences, P.O. Box 7072, Kampala, Uganda
4. Department of Epidemiology and Biostatistics, Makerere University School of Public Health, P.O. Box 7072, Kampala, Uganda
5. Johns Hopkins School of Medicine, 600 N. Wolfe Street, Baltimore, MD 21287, USA
6. Department of Disease Control and Environmental Health, Makerere University School of Public Health, P.O. Box 7072, Kampala, Uganda
7. Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, 627 N. Washington Street, Baltimore, MD 21205, USA