1. Public Health - Seattle & King County, HIV/STD Program, Seattle, USA
2. Department of Epidemiology, University of Washington, Seattle, USA
3. Department of Medicine, University of Washington, Seattle, USA
4. Department of Biostatistics, University of Washington, Seattle, USA
5. Department of Anthropology, University of Washington, Seattle, USA
6. Division of HIV/AIDS Prevention, Centers for Disease Control and Prevention, Atlanta, USA