Risk factors for incident HIV infection among anonymous HIV testing site clients in Santos, Brazil: 1996-1999

Objectives: To determine temporal trends in HIV infection and risk factors among persons seeking anonymous HIV testing in Santos, Brazil. Methods: Data and sera from persons testing for HIV from 1996 to 1999 were used. Exposures were abstracted from HIV testing risk assessments. Stored HIV-positive sera were tested to identify recently acquired HIV infection using a serologic testing algorithm for detecting recent HIV seroconversion (STARHS). Independent associations between exposures and recently acquired HIV infection were determined using multivariate analyses. Results: Overall, estimated HIV incidence was 2.0% (95% CI: 1.1-3.5) for the 4-year period: 1.2% (95% CI: 0.5-2.6) in women and 2.7% (95% CI: 1.3-5.0) in men. Incidence increased among women but remained stable among men. Exposures independently associated with incident infection included a history of sex work (OR = 5.4, 95% CI: 1.5-18.7), concurrent syphilis infection (OR = 4.1, 95% CI: 1.4-11.9), anal sex (OR = 3.0, 95% CI: 1.3-7.1), and having an HIV-positive sexual partner (OR = 1.4, 95% CI: 1.1-1.9). Conclusions: This study further demonstrates the public health utility of using the STARHS for the assessment of emerging trends in the HIV epidemic. Results from this study will help to target appropriate prevention strategies directed toward at-risk populations in Santos.