Estratégias de rastreamento da doença de chagas em área endêmica no Brasil

Abstract

Chagas disease (CD), caused by the protozoan Trypanosoma cruzi, is considered one of the top 20 neglected tropical diseases that still afflict many countries in Latin America, including Brazil. The objective of this dissertation was to describe strategies for tracking Chagas disease in an endemic region in Brazil, and for this purpose two studies were carried out. 1) The first study aimed to analyze the prevalence and factors associated with new confirmed cases of CD, identified by serological screening conducted based on the presence of clinical and epidemiological risk factors established in the Clinical Protocol and Therapeutic Guidelines for Chagas disease. This is an analytical cross sectional study with data from the Center for Research in Tropical Medicine of São Paulo-Minas Gerais (SaMi-Trop) carried out in the cities of Espinosa and São Francisco. Data collection included a questionnaire with closed questions and venous blood collection for CD serological testing. The result of this test was adopted as a dependent variable. The independent variables addressed personal issues, health conditions and permanent housing. Descriptive analysis of individual variables was performed. Subsequently, a bivariate analysis was performed using Pearson's chi-square test. The households that had positive individuals for CD were georeferenced, and the spatial distribution analysis was performed using the quartic function to estimate the nucleus density. A total of 2,038 individuals with no previous diagnosis of CD participated in the study. Among them, 188 participants (9.2%) were positive for CD. The profile of participants with positive serology for CD was associated with place of residence, age, relative with CD and living conditions. Our study demonstrates that, both in rural and urban areas, there are still CD patients who are unaware of their diagnosis. 2) The objective of the second study was to perform a CD serological screening in humans living in areas with vectors infected by T. cruzi, based on the strategy of the Chagas Disease Control Program, and to describe the prevalence and individual characteristics of the participants. This is an analytical cross-sectionalstudy conducted in four locations in Espinosa, Minas Gerais, Brazil. Data and samples from 56 participants were collected from 24 households, where 56 triatomine bugs infected with T. cruzi had been captured. The variables analyzed were the result of the ELISA test, dichotomized into two categories (negative/inconclusive vs. positive) and personal issues, health conditions and housing during life. Among the participants, 10 individuals (17.9%) had a positive serological test for CD. Thus, it was possible to identify individuals diagnosed with CD through the strategy based on the PCDCh, in addition, the presence of autochthonous vectors infected with T. cruzi in the home environment was observed. Factors such as age, having family members with CD, having lived in an area with a barber shop and in a wooden, wattle and daub or adobe house are associated with the transmission of T. cruzi. In view of this, the PCDCh must be strengthened, as it constitutes an effective screening strategy to identify individuals affected by CD, in addition to maintaining active entomological surveillance. According to these studies, it is concluded that screening strategies with different approaches proved to be efficient in identifying individuals with positive serology for CD. It is noteworthy that the population will benefit from the combination of the two screening strategies, providing access to diagnosis, treatment and/or specialized monitoring, in addition to maintaining active entomological surveillance.