A riqueza de espécies de reservatórios prediz taxas locais de mortalidade por doença de Chagas?

Abstract

The dilution effect hypothesis postulates an inverse relationship between host diversity and the probability of disease transmission. However, the amplification effect hypothesis proposes that there is a direct relationship between pathogen transmission and greater host diversity. Understanding the diversity of vectors, hosts and reservoirs of the etiologic agent Trypanosoma cruzi can contribute to the development of epidemiological surveillance of Chagas disease. We aimed to test the dilution and amplification hypotheses, considering the possible relationship between mortality rates from Chagas disease and the biodiversity of reservoir species of the disease. We used Chagas disease mortality data for each municipality in the country for the years 2018, 2019 and 2020; geographical coordinates for each city, human population density data and HDI for each municipality; rasters indicating species richness and environmental variables based on the literature; and polygons with centroids, using QGIS software. Generalized Estimated Equation Models were used in the statistical analysis, with statistical significance set at p<0.001. We obtained an association between bird and mammal species richness and mortality from Chagas disease. The diversity of mammalian hosts increased the risk of transmission through the amplification effect. For birds, our results revealed the occurrence of the dilution effect. The results also point to the influence of geographical variation through the distribution of vectors and the prevalence of different host species. We found a positive relationship between HDI and Chagas mortality rates, denoting an urgent need to develop public health strategies. Thus, this study showed that a significant increase in the risk of transmission of Chagas disease is associated with a greater diversity of mammal species and indicated that a lower risk of transmission of the disease is associated with a greater diversity of bird species. Our study also showed that municipalities with higher human development indices had, on average, higher Chagas mortality rates. Our findings contribute to an understanding of the specific epidemiology of Chagas disease and prompt discussion of more effective approaches to the control and prevention of vector-borne infectious diseases in a comprehensive context that encompasses biological, social and economic variables.