Factors associated with the incidence of urban visceral leishmaniasis: an ecological study in Teresina, Piauí State, Brazil

Abstract

The objective of this study was to identify socioeconomic and environmental factors associated with the incidence of visceral leishmaniasis in the city of Teresina, Piauí State, Brazil. This was an ecological study based on 1,744 cases reported from 1991 to 2000, and the city's neighborhoods served as the unit of analysis. Mean annual incidence rates were related to socioeconomic and demographic indicators and a vegetation index derived from remote sensing images by means of spatial multiple linear regression models. The neighborhoods with the highest incidence rates were mostly located in the city's peripheral areas. Multivariate analysis identified an interaction between population growth and the vegetation index, so that areas with high population growth and abundant vegetation showed the highest incidence rates. The percentage of households with piped water was inversely associated with visceral leishmaniasis incidence. Spatial distribution of visceral leishmaniasis in Teresina during the 1990s was heterogeneous, and incidence of the disease was associated with the peripheral neighborhoods with the heaviest vegetation cover, subject to rapid occupation and lack of adequate sanitation infrastructure.

Relative Risk of Visceral Leishmaniasis in Brazil: A Spatial Analysis in Urban Area

“…Ecological studies performed in Teresina (the capital of Piauí State, northeastern Brazil) suggest a spatial correlation between a high incidence of VL and areas with less urban infrastructure and precarious life conditions [6], [30]–[31]. In Belo Horizonte, the wide distribution of water supply (98.7% of the population), sewage (91.1%), and waste collection (97.9%) services [20] likely reflect the higher degree of urbanization of the city.…”

Factores de riesgo en escenarios emergentes de leishmaniasis visceral urbana, Misiones, Argentina

“…El grado de escolaridad, entendido como indicador de la capacidad potencial del grupo para enfrentar dificultades e interpretar proactivamente la información de los medios masivos y de la comunicación especializada, se ha correlacionado positivamente con la protección contra la leishmaniasis visceral (18,(30)(31)(32).…”

Prediction of high-risk areas for visceral leishmaniasis using socioeconomic indicators and remote sensing data

“…First, the time interval between both periods analyzed implied in substantial modifications on the dimension and structure of the geographical area under study, including the incorporation on the validation sample of areas that were considered rural in the period of 1993–1996. Second, the data used to derive the predictive model refers to an epidemic period, while the validation sample entails endemic years [12,15]. It is reasonable to suppose that in epidemic situations, due to the typical large magnitude of transmission during these periods, the disease spreads more largely in the geographic space, affecting population subsets that could have eventually been spared in endemic periods.…”

“…The satellite images used in this study come from the Landsat Thematic Mapper 5 sensors, which have spatial resolution of 30 meters, in other words, it does not allow the discrimination of elements on the earth’s surface for areas smaller than 900 m 2 . However, VL studies that used medium spatial resolution were able to identify some elements related to vegetation coverage, soil use and patterns of urban occupation associated to the risk of the disease [12,22,24,25], but the difficulties and limitations of these images to properly characterize the local features that determine the pattern of transmission of VL on the urban context are evident [22]. In future studies, high spatial resolution images should be used to better define the local environmental features related to VL occurrence [26].…”