1. Perelman School of Medicine, University of Pennsylvania, Philadelphia
2. Division of Allergy and Infectious Diseases, University of Washington School of Medicine, Seattle
3. Department of Epidemiology, University of Washington School of Public Health, Seattle
4. Botswana-UPenn Partnership, Gaborone, Botswana
5. Department of Clinical Research, Faculty of Infectious Diseases and Tropical Medicine, London School of Hygiene and Tropical Medicine, United Kingdom