1. Division of Intramural Research, National Institute of Allergy and Infectious Diseases, National Institutes of Health, Bethesda, Maryland
2. Department of Epidemiology, Bloomberg School of Public Health, Johns Hopkins University, Baltimore, Maryland
3. Division of Infectious Diseases, Department of Medicine, Johns Hopkins University, Baltimore, Maryland
4. Department of Medicine Makerere University, Kampala, Uganda
5. Rakai Health Sciences Program, Entebbe, Uganda