The changing distribution of HIV infection: HIV surveillance in Lazio, Italy, 1985 through 1994. Lazio HIV Surveillance Collaborative Group.

OBJECTIVES: This study sought to describe the human immunodeficiency virus (HIV) surveillance system in Lazio, Italy, and to analyze exposure patterns and time trends of HIV serodiagnoses from January 1985 to December 1994. METHODS: A linkage procedure made it possible to identify newly diagnosed HIV cases. Anonymous information was collected on demographic and exposure factors for each individual. RESULTS: Of 35,425 reports, 13,660 were newly diagnosed HIV cases, 70.9% of them in men. The proportion of women increased at the beginning of the study period (the male:female ratio declined from 3.5 in 1985 to 2.6 in 1986) and then remained stable. The proportion of subjects reporting heterosexual exposure, in men and women, respectively, increased from 1.5% and 2.0% in 1985 to 21.2% and 60.8% in 1994. Starting in 1992, heterosexual contact has become the main transmission route for women. CONCLUSIONS: A changing pattern in the HIV epidemic is emerging, with a shift in the incidence of HIV diagnosis from "core" high-risk groups (drug injectors) to the large low-risk population (the general population) exposed through heterosexual transmission. This is probably occurring in other areas (e.g., large urban centers in the United States) with a similar epidemiological situation.