Prevalência de Chlamydia trachomatis e fatores de vulnerabilidade associados em uma população ribeirinha da Amazônia brasileira

Abstract

Introduction:Chlamydiatrachomatis is widely distributed in urban and non-urban populations, including riverside populations. These populations have low access to laboratory diagnosis in Primary Health Care and there are difficulties in clinical diagnosis, which do not allow the break of the chain of transmission. The riverside dwellers in the Brazilian Amazon live in an area of high incidence of sexually transmitted infections and have low socioeconomic indicators. There are no studies addressing the prevalence of Chlamydiatrachomatis and riverine populations in light of social, individual, and programmatic vulnerability factors. Objective: To identify the prevalence of Chlamydiatrachomatis and associated vulnerability aspects in an adult riverine population in the Brazilian Amazon. Method: Observational, cross-sectional study conducted among adult residents of Ilha do Combú, in the city of Belém. We adopted an expected frequency of 50%, acceptable margin of error of 5%, confidence level of 95%, design effect 1.0, which resulted in a sample of 306 participants, with an additional 8.5% being included considering a percentage of participants who did not answer or did not know. The sample size calculation was performed in the Statcalc - Sample size and power module of the EPI INFO Version 7.2.2.16 program. For data collection two questionnaires were applied, one validated and the other adapted, evaluated by judges and previously tested for the present research, with the intention of identifying the knowledge, attitudes and practices about sexually transmitted infections, besides socio-demographic data. The variables used to test the main hypothesis of the study were categorical: aspects of the individual, social and programmatic dimensions are associated with the chances of Chlamydia trachomatis infection among adult river dwellers. The dependent variable analyzed was reagent serology for CT. The diagnostic criterion for reagent serology was the detection of antibodies of the IgG and IgM classes of CT in an enzyme linked immunosorbent assay (ELISA). The independent variables analyzed corresponded to the vulnerability aspects described from the literature. To identify the prevalence of chlamydia, a peripheral blood sample was collected from the study participants. The sample then underwent analysis for IgG and IgM anti-Chlamydia trachomatis antibody detection by enzyme-linked immunosorbent assay (ELISA). Logistic regression was the method of choice for expressing the odds of finding markers of Chlamydiatrachomatis infection among those exposed to vulnerable conditions relative to the unexposed. Univariate binary regression was selected for multiple regression, adopting the stepwise model. All statistical analyses were done using Minitab 20® and Biostat 5.3® software. Significance level of 5%, 95% confidence interval (CI) and Chance Ratio (RC) were adopted. Results: The study sample consisted of 325 participants. The prevalence of Chlamydia trachomatis infection markers was 22% (72/325%; 95% CI: 17.5%; 26.4%). For the isolated IgM marker, the prevalence was 5.5% (6/109; 95% CI: 1.2%; 9.8%), with 100% of cases being female. Most participants had low educational level and low wage income, 56.6% (184/325) never attended school or had only elementary level; 68% (222/314) lived with monthly wage income less than one minimum wage. In the multiple logistic regression analysis, after adjustments, the participants who had their condom broken and were beneficiaries of government income transfer programs were almost twice as likely to have the presence of markers of Chlamydiatrachomatis infection when compared to those who did not have their condom broken. Conclusion: In this population, besides the low social conditions, vulnerability factors were found in the individual and social dimensions that increased the chances of infection by the bacteria, such as low education, low family income and poor access to health services. The identification of these aspects enables the choice of the most appropriate combined prevention strategy for these populations.