1. Division of Allergy and Infectious Diseases, Department of Medicine, University of Washington, Seattle, WA, USA
2. Centre for Microbiologic Research, Kenya Medical Research Institute; Nairobi, Kenya
3. Departments of Obstetrics and Gynecology and Global Health, University of Washington; Seattle, WA, USA
4. Departments of Epidemiology, Global Health, and Medicine, University of Washington; Seattle, WA, USA