Research Articles

Climatic and demographic determinants of American visceral leishmaniasis in northeastern Brazil using remote sensing technology for environmental categorization of rain and region influences on leishmaniasis

Remote sensing (RS) permits evaluation of spatial and temporal variables that can be used for vector-borne disease models. A Landsat Thematic Mapper scene covering Caninde, Ceara in northeastern Brazil (September 25, 1986) was spectrally enhanced and classified using ERDAS (Atlanta, GA) Imagine for 873 4-km2 areas. The population and number of cases of American visceral leishmaniasis (AVL) were determined for each 4-km2 area. Relative risk (RR) ratios were calculated for climate, demographic, and case data recorded for 17 years by the Municipality of Conide. The RR of AVL for a child less than 10 years old from the foothills relative to non-foothill residency was 4.0 (95% confidence limit = 3.5, 4.5). The RR of AVL in children was 9.1 during a time when the three-year rolling rain average (current year plus two previous year's precipitation) was between 40 and 60 cm relative to rain greater than 100 cm. The results suggest that features detected by RS techniques combined with climatic variables can be used to determine the risk of AVL in northeastern Brazil.