HIV incidence on the increase among homosexual men attending an Amsterdam sexually transmitted disease clinic: using a novel approach for detecting recent infections.

OBJECTIVE: Dramatic increases have occurred in sexually transmitted diseases (STD) and in sexual risk behaviour among homosexual men in Amsterdam and internationally. We investigated whether these trends indicate a resurgence of the HIV epidemic.
METHODS: HIV incidence was determined among homosexual attendees of an STD clinic in Amsterdam, who had participated in semi-annual anonymous unlinked cross-sectional HIV prevalence studies from 1991 to 2001. Stored HIV-seropositive samples were tested with a less-sensitive HIV assay and, if non-reactive, were further tested for the presence of antiretroviral drugs, indicative of the use of highly active antiretroviral therapy. Seropositive men who tested non-reactive on the less-sensitive assay and had not used antiretroviral drugs were classified as recently infected (< 170 days). Annual HIV incidence and its changes were examined.
RESULTS: Among 3090 homosexual participants (median age 34 years), 454 were HIV infected, of whom 37 were recently infectioned. From 1991 to 2001 the overall incidence was 3.0 infections/100 person-years. Incidence increased over time (P = 0.02) and, strikingly, the increase was evident in older (> or = 34 years) men (P < 0.01), but not in the young. Of men recently infected, 84% (n = 31) were unaware of their infection and 70.3% (n = 26) had a concurrent STD. These 26 men reportedly had sex with a total of 315 men in the preceding 6 months.
CONCLUSION: HIV incidence is increasing among homosexual attendees of an STD clinic. It is imperative to trace recently infected individuals, because they are highly infectious, and can thus play a key role in the spread of HIV.