EVIDENCE FOR RECENT GROWTH OF THE HIV EPIDEMIC AMONG AFRICAN-AMERICANMEN AND YOUNGER MALE COHORTS IN LOS-ANGELES-COUNTY

To estimate the recent course of the human immunodeficiency virus type 1 (HIV) epidemic among men within birth cohorts, ethnic groups, and H IV-risk groups in Los Angeles County, backcalculation methods were com bined with log-linear models and census data to reconstruct HIV incide nce in subgroups from AIDS surveillance data. Results were compared wi th directly measured HIV seroprevalence in public sexually transmitted disease (STD) clinics in Los Angeles. Models of HIV incidence indicat e that the initial epidemic pattern among men who have sex with men, i ncluding a decline in incidence since the mid-1980s, does not apply to all post-1960 birth cohorts. Later peaks were observed in younger bir th cohorts and among injection drug users, especially among African-Am erican men, with no evidence of a peak before the 1990s among men born after 1960. Our results indicate that HIV continued to spread near pe ak rates into the 1990s among younger birth cohorts, especially among young African-American men who have sex with men. Because of the lengt hy incubation period from HIV infection to AIDS incidence, our results imply that the AIDS epidemic has not yet peaked in these cohorts and may continue to grow through the present decade in several subgroups. The large variation in HIV incidence and prevalence across birth cohor ts and other subgroups needs to be addressed in future community inter vention plans.