1. Department of Medical Microbiology, University of Nairobi, Nairobi, Kenya.
2. Department of Global Health, University of Washington, Seattle, Washington.
3. Kenya Medical Research Institute, Nairobi, Kenya.
4. Department of Pediatrics, University of Nairobi, Nairobi, Kenya.
5. Fred Hutchinson Cancer Research Center, Seattle, Washington.
6. Department of Epidemiology, University of Washington, Seattle, Washington.
7. Department of Medicine, University of Washington, Seattle, Washington.
8. Department of Pediatrics, University of Washington, Seattle, Washington.