[1] Los Angeles Cty Dept Hlth Serv, HIV Epidemiol Program, Los Angeles, CA 90005 USA
[2] Univ So Calif, Dept Prevent Med, Keck Sch Med, Los Angeles, CA 90089 USA
[3] Univ So Calif, Los Angeles Cty Med Ctr, Los Angeles, CA 90033 USA
[4] Harbor UCLA Med Ctr, David Geffen Sch Med, Los Angeles Biomed Res Unit, Torrance, CA 90509 USA
[5] Ctr Dis Control & Prevent, Atlanta, GA USA