Incidence, risk factors and genotyping in HIV-infcted men who have sex with men: a cohort study in Argentina.

SEGURA M; BAUTISTA CT; PANDO MA; SOSA ESTANI S; MARONE R; FERNANDEZ M; SANCHEZ J; CARR JK; WEISSENBACHER M; AVILA MM

Toronto

Conferencia; XVI International AIDS Conference; 2006

IAS

Background: Previous cross-sectional studies have documented that men who have sex with men (MSM) constitutes one of the risk groups with the highest HIV prevalence (13.8%) in Argentina. In order to determine the incidence rate and molecular epidemiology of HIV among MSM, a cohort prospective study was performed. Methods: The MSM cohort study was conducted in the city of Buenos Aires from February 2003 to December of 2004. HIV testing was done by ELISA and confirmed by Western blot assay. Sociodemographic, sexual risk behaviors data and a blood sample for HIV testing were collected at baseline, 6 and 12 months. Cox regression analysis was applied to determine risk factors associated with seroconversion. HIV-positive samples were analyzed by partial sequencing of the protease and the reverse transcriptase regions (Pro/RT). Results: A total of 811 participants were enrolled at baseline. Of them, 327 HIV-negative volunteers aged 18 to 60 years old were followed–up for one-year. Retention rates at 6 and 12 months were 97% and 92%, respectively. Twelve MSM seroconverted for HIV infection, yielding an HIV incidence rate of 3.9/100 person-years (95% CI = 2.0-6.7). A greater number of different sexual contacts (10 or more in the last 6 months) were statistically associated with HIV seroconversion (Hazard ratio = 3.3, 95% CI: 1.1­10.4). By partial pro/RT genotyping analysis, 10 (83%) HIV-positive samples were subtype B and 2 (17%) samples were BF recombinants. Conclusions: Although, only a predictive factor was associated with HIV seroconversion, HIV incidence rate in this population was high. As observed in previous studies, subtype B was predominant in this group of MSM. Focused and larger prospective epidemiologic studies are needed to better identify prevailing sociodemographic and risk behavior patterns responsible for HIV incident cases in order to more efficiently implement control and prevention measures in Argentina.