Trends in unsafe sex and influence of viral load among patients followed since primary HIV infection, 2000-2009.

Background: In the current context of increasing unsafe sex, HIV incidence may have evolved, depending on HIV prevalence in sexual networks and, among HIV-infected persons who practice unsafe sex, on their infectivity and partners' HIV serostatus. We examined calendar trends in sexual behaviours at risk of HIV-1 transmission (SBR) among 967 adults followed since primary HIV infection (ANRS PRIMO cohort) and relationship with current treatments and viral load. Methods: Patients completed since 2000 self-administered questionnaires on sexual practices every 6 months. SBR with HIV-negative/unknown partners were analyzed among 155 heterosexual women, 142 heterosexual men and 670 MSM by using logistic generalized estimating equation models (6656 visits). Results: During 2000-2009, the frequency of SBR did not increase significantly among women with steady partners; risk factors were a low education level and alcohol/ smoking use. Among heterosexual men with steady partners, the frequency of SBR doubled since 2006; during this period, the only associated factor was combined antiretroviral treatment for at least 6 months or viral load less than 400copies/ml. Among MSM, SBR increased gradually over time; SBR with steady partners was associated with a low education level and alcohol use. SBR was more frequent among MSM with casual partners; no association with viral load was found. Conclusion: In France, recent trends and risk factors in unprotected sex with HIV-negative/unknown partners differ according to sex/sexual preference. The recent increase in SBR among heterosexual men with low viral load may be related to increasing awareness of the 'treatment-as-prevention' concept. The lack of association between SBR and viral load among MSM supports use of treatment-as-prevention as part of diversified prevention strategies.