A proporção de Mata Atlântica remanescente no entorno de áreas urbanas relaciona-se à incidência de dengue?

Abstract

Deforestation alters the landscape and resulting in a change in biotic and abiotic conditions of the remaining vegetation and mostly deforested areas. Such changes may alter the habitats occupied by vectors increasing occurrence of diseases linked to the environments in which there were fragmentation or new areas devastated. Considering the dengue vector-borne disease, its occurrence may decrease in areas with vegetation cover, by reducing the vectorial capacity of mosquito vectors, the result of environmental conditions less favorable to the life cycle of the same. The remnants of vegetation can also be an aggravating factor for the occurrence of dengue, functioning as a haven for mosquitoes during the urban area becomes unsuitable for survival. In this work, two studies were performed, separated into two chapters. In the first chapter, we used the prevalence of Dengue in 67 counties, examining whether there is a relation between the disease, land cover, population size, PIB and IFDM. Through simple regressions, the following hypotheses were examined: i) the proportion of vegetation in the vicinity of the Atlantic cities will influence the prevalence of the disease? There were two methodologies such circumstances: a) From the dimensions and size of county population, we obtained a radius around the urban area, called "area of influence" within which the entire Atlantic Forest vegetation was measured. b) from a buffer of 500 meters around the area of the town, checking out all the fragments of vegetation that touch the buffer. Every piece that touched the buffer has been fully measured. No effect of the Atlantic Forest on the incidence of dengue in both samples ("area of influence": n = 67, p = 0.15, R² = 0.06, “buffer”: n = 67, p = 0.1, R² = -0.01). ii) The municipal populations will influence the proportion of people sick? There was no relationship between variables (n = 67, p = 0.09, R² = 0.1). iii) PIB per capita of cities will influence the proportion of people sick? There was a relationship between variables (n = 67, p = 0.00, R² = 0.42). iv) The IFDM municipalities will influence the proportion of people sick? was no relationship between the variables: n = 67, p = 0.70, slope = -1.24, R² = -0.01. The second chapter collected data MosquiTRAP trap in the city of Governador Valadares, to see if there are preferred foraging areas of Aedes aegypti and Aedes albopictus in relation fragments of Atlantic Forest vegetation, immersed in the urban area and its surroundings. It was also noted that there are differences in catch relative to the amount of vegetation (urban forestry) around the trap. We tested the following hypotheses: i) There is difference of catch of mosquitoes in relation to the distances that the traps are fragments and the amount of trees in the surrounding areas? For analysis with Ae. albopictus, we used multiple regression and no significant relationship was observed (Distance: p = 0.2118, slope = 0.00, R ² = 0.03; Area Vegetation: p = 0.0921, slope = 0.00, R² = 0.03). Considering the vector Ae. aegypti, we used multiple logistic regression and there was no relationship between the presence of his capture with the distances of the fragments and areas of vegetation around the trap (Distance: p = 0.30; Area Vegetation: p = 0.989). ii) There is a difference in the capture of the vectors in periods of drought and rain? We used t test for dependent samples and there was no statistical difference in the capture of mosquitoes in two periods: Ae. aegypti (t = -1.854, p = 0.07), Ae. albopictus (t = 1.31, p = 0.19). iii) There is a relationship between capture and vectors of dengue cases? Simple regression was used and there was a significant relationship between the capture of Ae. aegypti and dengue fever (p = 0.027, slope = 1.71, R² = 0.41). However, there was no relationship between the capture of Ae. albopicuts and dengue fever (p = 016, slope = -1.27, R² = 0.13). These results, taken together, show that the climate, seasonal and socioeconomic factors are more relevant than the presence or amount of vegetation for disease transmission and should be considered when planning measures to control the vector Ae. aegypti. However, it is necessary studies that address the importance of fragments of vegetation in the life cycle of mosquitoes, since the interior and edges of vegetation biotic and abiotic conditions are very different from urban areas, the vegetation may serve as a place of refuge for mosquitoes in the period that the conditions of the urban area becomes unfavorable.