San Francisco Department of Public Health, 101 Grove Street, Room 308, San Francisco, CA 94102, USA. mitch_katz@dph.sf.ca.us
OBJECTIVES: This study assessed the countervailing effects on HIV incidence of highly active antiretroviral treatment (HAART) among San Francisco men who have sex with men (MSM). METHODS: Behavioral risk was determined on the basis of responses to cross-sectional community interviews. HIV incidence was assessed through application of an enzyme-linked immunoassay testing strategy. RESULTS: Use of HAART among MSM living with AIDS increased from 4% in 1995 to 54% in 1999. The percentage of MSM who reported both unprotected anal intercourse and multiple sexual partners increased from 24% in 1994 to 45% in 1999. The annual HIV incidence rate increased from 2.1% in 1996 to 4.2% in 1999 among MSM who sought anonymous HIV testing, and the rate was high (5.3%) but stable in a blinded survey of MSM seeking sexually transmitted disease services. CONCLUSIONS: Any decrease in per contact risk of HIV transmission due to HAART use appears to have been counterbalanced or overwhelmed by increases in the number of unsafe sexual episodes.