Classes of Soil Use and Climatic Patterns in Hantavirus Transmission Areas, São Paulo State, Brazil

Abstract

ISEE-235 Objective: The objective of this study was to identify local climatic patterns and the use and occupation of soil in hantavirus pulmonary syndrome (HPS) transmission areas in São Paulo State, Brazil, from 1993 to 2005. Material and Methods: A series of multispectral and multitemporal remote sensing images were used from LANDSAT5-TM and LANDSAT7- ETM+, related to disease transmission year. Images were recorded in digital format, segmented, and classified for homogenous region grouping. In this step, images were interpreted and checked against field collected data. SPRING software was used to integrate and manipulate database data. Rainfall was analyzed in the months and years when cases occurred and compared with means plus or minus one standard deviation from 4 decades (1960–2005) using Ministry of Agriculture data (Agritempo). Results: We identified pastures with “braquiária” (Brachiaria decumbens) as the main component, in the 4 cerrado (Cássia dos Coqueiros, Ribeirão Preto, Tupi Paulista, and Aguaí), and the planalto (São Carlos) study regions. All studied areas were near forest. Also grain and vegetable crops were frequently found close to patient homes. In the Atlantic Forest region we found deforestation and anthropized areas (Juquitiba). HPS showed marked seasonality in cerrado areas, with a common pattern of higher incidence in months with lower rainfall than the average for the last 40 years. Conclusions: In recent years seasonal crops have been replaced by pastures and braquiária, reducing biodiversity favoring opportunist and specialist rodent species. This is the case with Bolomys lasiurus, the main HPS vector in the Brazilian cerrado. Environmental and ecologic changes favor the emergence of new disease and the reemergence of old ones.