1. HIV Epidemiology Program, Los Angeles County Department of Public Health, Los Angeles, California.
2. Department of Preventive Medicine, USC Keck School of Medicine, Los Angeles, California.
3. Los Angeles Biomedical Research Institute at Harbor-UCLA Medical Center, Carson, California.
4. AIDS Healthcare Foundation, Los Angeles, California.
5. Los Angeles County-USC Medical Center, Los Angeles, California.
6. Kaiser Permanente, Los Angeles, California.