HIV seroincidence in a population of men having sex with men from Buenos Aires, Argentina.

AVILA MM; VIGNOLES M; MAULEN S; SHEPPARD H; SOSA ESTANI S; PANDO MA; MARTINEZ PERALTA L; WEISSENBACHER M

Barcelona

Conferencia; XIV International AIDS Conference; 2002

IAS

Background: According to the Argentine National AIDS Program's 2001 report, in Argentina at the beginning of the epidemic (1982-1990), men having sex with men (MSM) represented 60% of the total notified AIDS cases, decreasing to 28% in 1999. However, AIDS cases in MSM have increased slightly since then. The knowledge of HIV incidence is necessary for a better understanding of the current HIV infection dynamics and is essential for planning HIV vaccine clinical trials. The Serologic Algorithm for Recent HIV Seroconversion (STARHS) strategy has the ability to distinguish recent from older infections, permitting the estimation of HIV incidence. It combines the use of a sensitive enzyme immunoassay (EIA) with a modified, less sensitive (LS) version of this EIA. Our objective was to estimate the HIV-1 seroincidence in a gay population using the STARHS strategy and a follow-up survey. Methods: 694 MSM, who visited a counseling and testing center at a non governmental organization in Buenos Aires from March 2000 to March 2001, were tested for HIV infection. Plasma samples from 90 of these men, HIV-1 seropositive by CDC interpretative criteria (90.5% subtype B by HMA), were tested by the modified Organon Teknika Vironostika® HIV-1 EIA (LS-EIA) and HIV-1 seroincidence was estimated using the STARHS strategy. In the follow-up survey, 221 HIV-1 seronegative MSM were retested for HIV infection. The follow-up periods had a mean of 9.08 months (SD=3.9). Results: The estimated HIV annual seroincidence was 6.68% (95%CI, 3.10-11.29%) using the STARHS strategy and the estimated seroincidence density was 6.00% person/years (95%CI, 3.10-11.00) based on the follow-up survey.  Conclusions: The two strategies show similar results in this population. The estimated HIV seroincidence by both studies indicates current high risk in the MSM population, which could be considered suitable for entering HIV  vaccine clinical trials.