Acute retrovirus syndrome among prospectively identified homosexual men with incident HIV infection in Brazil. Projecto Praça Onze Study Group.

BACKGROUND: Symptoms associated with HIV infection are common among HIV seroconverters, but the acute retroviral syndrome (ARS) is a diagnostic challenge because of the absence of a sensitive and specific case definition. We conducted an analysis of HIV seroconverters in Projeto Praça Onze, a HIVNET HIV seroincidence study among homosexual men in Rio de Janeiro. METHODS: Information from study subjects enrolled in Projeto Praça Onze who were documented HIV seroconverters were compared with nonseroconverters. At each semiannual study visit, participants were asked about HIV seroconversion symptoms and sexually transmitted diseases (STDs) during the preceding 6 months. All information was collected before the laboratory evaluation. A classification tree analysis was used to identify an ARS case definition, first using clinical information and then after including risk factor data for seroconversion in our cohort. RESULTS: As of July 1998, 674 volunteers were enrolled and 34 of these seroconverted; information was available for 33 of these. Among the seroconverters, 11 (34%) denied any symptoms, and 22 (66%) reported one or more symptoms, the most common of which were fever (25% of seroconverters versus 7% of nonseroconverters; p <.01), night sweats (9% versus 2%, respectively; p =.05), incapacitating disease (ID) for >/=3 days (27% versus 7%, respectively; p <.001), and weight loss of >/=2 kg (21% versus 9%, respectively; p =.05). STDs were more common in seroconverters (gonorrhea: 9% versus 1%, respectively; p <.01 and condyloma: 9% versus 3%, respectively; p =. 08). The first case definition was ID for >3 days, fever, pharyngitis, and myalgia (seroconverters, 3 of 32, versus nonseroconverters, 2 of 640). The second case definition was was ID for >3 days, anti-core hepatitis b-positive, and age <21 years (seroconverters: 6 of 32 versus nonseroconverters 4 of 640). The sensitivity and specificity for the first and second case definitions were: 9.4%, 99.4%, and 18.8%, 99.8%, respectively. CONCLUSIONS: Among HIV seroconverters, symptoms consistent with ARS were common. We were unable to identify a sensitive case definition that could be used as a screening tool. Although the clinical case definition was not validated, the specificity of our case definitions was high, suggesting that subjects within this HIV risk group who fulfill the case definition should be tested for HIV.

Identification of a high-risk heterosexual population for HIV prevention trials in Rio de Janeiro, Brazil. Projeto Praço Onze Study Group.

The study of interventions to prevent HIV transmission requires access to populations with a high rate of HIV transmission. We estimated HIV incidence among heterosexual males and females who were seen at an HIV testing site in Rio de Janeiro, Brazil. Stored sera from individuals who visited the site between March and December 1998 were analyzed using the sensitive/less sensitive (S/LS) assay and a chart abstraction was performed. During the study period, 6353 serum samples were tested. Of those tested, 1203 were found to be HIV-seropositive or indeterminate, of which 1050 (87%) remained available for further testing. In addition, 84 serum samples, representing 63 adults, were found to produce results suggesting early HIV infection. Of these, 14 were heterosexual and female (median age, 38 years), and 19 were heterosexual and male (median age, 25 years). The estimated HIV seroincidence was 1.9 (95% confidence limits (CL), 0.9%-3.9%) and 2.8 (95% CL, 1.4%-5.3%) per 100 person-years among heterosexual women and men, respectively. A survey on willingness to participate in future placebo-controlled HIV vaccine trials in this population indicated that 54.5% and 53.9% of heterosexual women and men, respectively, indicated that they would definitely be willing to participate. We have identified a heterosexual population in Rio de Janeiro with a high rate of HIV transmission willing to participate in placebo-controlled vaccine trials. This study demonstrates the usefulness of the newly described S/LS assay, which allows one to estimate HIV incidence from single serum specimens.

Willingness to participate in HIV vaccine trials among men who have sex with men in Rio de Janeiro, Brazil. Projeto Praça Onze Study Group.

Evaluation of HIV vaccines requires high-risk individuals willing to participate in a vaccine trial. We investigated the willingness to participate in HIV vaccine trials of initially HIV-seronegative homosexual men enrolled in an HIV seroincidence cohort study. Of 815 initially HIV-seronegative participants, 569 (69.8%) reported willingness to participate in an HIV vaccine trial. Altruism was the primary reason given for wanting to participate. Fear of HIV infection from the study's immunizations and a vaccine-induced positive HIV test result were the main reasons for not wanting to participate. Of the 34 study subjects who eventually had HIV seroconversion, 29 (85%) had indicated a willingness to participate. In a univariate analysis, factors associated with willingness to participate included HIV seroconversion during follow-up (odds ratio [OR]. 2.6; p =.04), low educational level (OR, 1.6; p =.005), low family income (p =.02), and exchanging sex for housing, food, or clothing (OR 6.1; p =.005). Students were less likely to be willing to participate in a trial (OR, 0.7; p = .03), as well as those who reported sex at the first encounter (OR, 0.7; p = .05). In a multivariate analysis, low education level, infection with Condyloma, and exchanging sex for housing, food, or clothing were positively associated with willingness to participate, whereas being a student and reporting sex at first encounter were negatively associated. In general, factors indicative of high-risk of HIV infection were associated with a higher willingness. These data demonstrate that this high-risk homosexual male cohort has a high willingness to participate in HIV vaccine trials.

Incident HIV infection in a high-risk, homosexual, male cohort in Rio de Janeiro, Brazil.

An HIV seroincidence study was conducted to identify a high-risk population for HIV prevention trials. Inclusion criteria were male gender, homosexual behavior, age between 18 and 50 years, and negative HIV serostatus; 862 study subjects were screened and 753 were enrolled and observed during follow-up for a mean of 1.5 years. In this population, 34 people had HIV seroconversions for an overall annual seroincidence of 3.1% (95% confidence interval [CI], 2.1%-4.1%). Among study subjects <20 years old, annual incidence was 8.4% (95% CI, 1.7%-15%). Independent risk factors for seroconversion were age <25 years (p = .01), hepatitis B core antibody seropositivity (p > .01), sex at first encounter in the preceding 6 months (p = .11), and a history of gonorrhea or condyloma in the 6 months before seroconversion (p = .04 and p = .08, respectively). At enrollment, 85% of the eventual seroconverters said they would participate in a vaccine trial; all agreed to participate when told there would be a placebo arm. Follow-up rates were 97%, 91%, and 88% at 6, 12, and 18 months, respectively. The HIV-1 subtype was B for each of the first 17 seroconverters. These data demonstrate the suitability of this cohort for HIV prevention trials, based on high HIV incidence and retention rates, and a willingness to participate in such trials.