Background: A substantial decline of HIV prevalence has been observed in injection drug users (IDUs) from Rio de Janeiro, in recent years. Differential characteristics and behaviors of new (injecting for <6 years) and long-term (>=6y) injectors may help to understand recent changes and to implement appropriate prevention strategies.
Methods: Between October 1999 and December 2001, 609 active/ex-IDUs were recruited from different communities, interviewed, and tested for HIV. Contingency table analysis and t-tests were used to assess differences between new and long-term injectors. Multiple logistic regression was used to identify independent predictors of HIV serostatus for long-term and new injectors.
Results: HIV prevalence was 11.7% for 309 long-term injectors (95% CI 8.1-15.3) and 4.3% for 300 new injectors (95% CI 2.0-6.6). New injectors reported having engaged in treatment and having received syringes from needle exchange programs (NEPs) more frequently than long-term injectors in the last 6 months, but sharing behaviors remained frequent and even increased vis-à-vis long-term injectors. For male new injectors, "sexual intercourse with another man" was found to be the sole significant risk factor for HIV infection (Adj OR = 8.03; 95% CI 1.52-42.48). Among male long-term injectors, "to have ever injected with anyone infected with HIV" (Adj OR = 3.91; 95% CI 1.09-14.06) and to have "ever been in prison" (Adj OR = 2.56; 95% CI 1.05-6.24) were found to be significantly associated with HIV infection.
Discussion: New injectors are seeking help in drug treatment centers or needle exchange programs. They differ from long-term injectors in terms of their risk factors for HIV infection and have lower prevalence levels for HIV. Such differences may help to understand the recent dynamics of HIV/AIDS in this population and highlight the need to reinforce new injectors' help-seeking behavior and to reduce current unacceptably high levels of unprotected sex and syringe sharing in new injectors despite attendance of prevention/treatment programs.