Características ambientais e a ocorrência de leishmaniose visceral em Teresina, Piauí: uma aplicação utilizando sensoriamento remoto

Abstract

In the Americas, visceral leishmaniasis (VL) undergoes an active process of urbanization and the domestic dog is considered to be the main reservoir of the disease in this scenario, although its role in the transmission cycle is not fully explained. This study aimed to investigate, by spatial data analysis and remote sensing images, the association between environmental factors with the occurrence of canine infection by Leishmania chagasi and their spatial correlation with the human disease in the city of Teresina (Piauí-Brazil), where first urban epidemic of LV in Brazil was reported. The results are presented in the form of two manuscripts, which used georeferenced data obtained through a serological canine survey carried out during 2011 canine, in localities with moderate or severe transmission. In the first manuscript, the multilevel logistic regression approach was used to correlate the prevalence of canine infection with the environmental variables of grids with 900m2 (30mx30m) where the residence was located, adjusting to the dogs' individual characteristics (gender, age and race) and characteristics of the residences. The environmental analysis was performed with 717 dogs distributed in 494 households and 396 grids. The percentage of the area of grid covered by clear pavement (bare soil or old asphalted streets) >16.5% was the only environmental variable associated with canine infection by L. chagasi (Odds ratio [OR] = 2.00, 95% confidence interval [95% CI]: 1.22 - 3.26). These probably correspond to impoverished areas with inadequate infrastructure suggesting the occurrence of an urban cycle similar to those observed in rural and periurban areas. In the second manuscript, by the hierarchical analysis of nearest neighbor, were checked seven clusters of highest concentration of seropositve dogs in relation to seronegative in less urbanized areas with sparse vegetation. This analysis was performed with 322 dogs distributed in five boroughs. The spatial relationship between seropositive dogs and human cases was investigated by the method of average distance between points and was analyzed by t-test. The human cases were closer to the seropositive dogs when compared to the distance from the seronegative ones, suggesting the existence of a spatial relationship between the human LV and canine infection. The results contribute to a greater understanding of the dynamics of urban disease and also provide useful information for the prevention and control of visceral leishmaniasis in humans.