Environmental factors affecting transmission risk for hantaviruses in forested portions of southern Brazil.

Using ecological niche modeling approaches, we assessed suites of environmental factors to identify areas of transmission risk in forested regions of southern Brazil. We studied all officially confirmed cases from the Epidemiological Surveillance System of the Brazilian Health Ministry from Atlantic Forest and Araucaria forest areas of southern Brazil (n=264), during 1993-2008. Among climate-related influences associated with hantavirus cases, winter precipitation and high photosynthetic mass (EVI) were particularly closely related to case distributions. Models identified broad risk areas for hantavirus transmission, extending along the coastal Atlantic Forest region from São Paulo to Rio Grande do Sul, eastern Paraguay, and Argentina. Host distribution maps indicate overlap of several species of Oligoryzomys in the transmission area, showing the necessity of more detailed reservoir-based studies to detect finer-scale infection foci.