1 Department of Environmental and Occupational Health, Milken Institute School of Public Health, George Washington University, Washington D.C. Department of Medicine.
2 Department of Pathology, Johns Hopkins School of Medicine Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland.
3 Department of Epidemiology, Johns Hopkins Bloomberg School of Public Health, Baltimore, Maryland Rakai Health Sciences Program, Entebbe, Uganda.