Flutuação mensal de Lutzomyia longipalpis em área urbana de transmissão intensa de Leishmaniose visceral no Tocantins e correlação com fatores climáticos

Abstract

The state of Tocantins has recorded, in recent years, the highest incidence of Visceral Leishmaniasis (VL) in the northern region of Brazil, and the municipality of Araguaína is among those that report the most cases, being classified as an area of intense transmission of the disease. Considering the importance of entomological studies for the knowledge of the epidemiological chain of Visceral Leishmaniasis in a region, this study aimed to determine the monthly fluctuation pattern of the population of Lutzomyia longipalpis in areas of the urban area of the municipality of Araguaína-TO and to evaluate the action of climatic variables on populations. For the entomological survey, systematic captures of sandflies were carried out, using light traps installed in the peridomicile and intradomicile of selected residences in eight districts of the urban area of the municipality of Araguaína, where human cases of VL were reported. The captures were carried out from November 2020 to October 2021 and the captured sandflies were identified and the species Lu. longipalpis accounted for. Lu. longipalpis was captured at all collection points, totaling 3.380 specimens, with the number of males captured (2.609; 77.2%) being significantly higher than the number of females (771; 22.8%). The number of sandflies captured in the peridomicile (2.099) was significantly higher (p=0.017) than indoors (1.281) and in the months with the highest rainfall (p<0.001). Considering the climatic data referring to the collection dates, the relative humidity of the air showed a moderate positive correlation with the number of sandflies captured (r=0.41; p=0.0129), wind speed showed a moderate negative correlation (ρ= - 0.53; p=0.013) and precipitation weak positive correlation (ρ= 0.38; p=0.024), but when considering the monthly values of climate variables in the correlation analysis, a strong positive correlation was observed (ρ>7) in relation to precipitation (ρ=0.82; p=0.001), relative humidity (r=0.76; p=0.004) and cloudiness (r=0.87; p<0.001) and a strong negative correlation was found in in relation to the insolation variable (r=-0.83; p<0.001). The information in this study can help in understanding the epidemiology of VL in the municipality of Araguaína, expanding the knowledge of factors related to the ecoepidemiology of vectors in the region, thus contributing to the bodies linked to the unified health system in directing control actions, mainly, those related to the vector.