1. Department of Obstetrics, Gynecology and Reproductive Sciences, University of California, San Francisco, San Francisco, California.
2. Doris Duke Clinical Research Fellow, University of California, San Francisco, San Francisco, California.
3. Department of Medicine, HIV/AIDS, University of California, San Francisco, San Francisco, California.
4. Center for Microbiology Research, Kenya Medical Research Institute, Nairobi, Kenya.