A case-control study of premises with one or more infected equids was conducted during the 2000 epizootic of West Nile virus (WNV) in the northeastern United States. Site-specific information was collected regarding the geographic location of animals, management practices used, and environmental characteristics in and around each affected premises. Statistical comparisons of case-control data were used to identify potential factors that might be linked to increased risk of infection. Also, spatial statistical analyses were used to assess case clusters. Risk factor data were combined with the results of cluster tests to describe the spatial pattern of disease spread. Introduction of virus into an area appears to be a random event associated with the density of infected wild birds entering a suitable focus. Infections occurring in proximity to a focus are spatially associated. The probability of equid infection was significantly correlated with proximity to wild bird roosts or to congregations of waterfowl. The role of vector mosquitoes associated with avian and mammalian transmission cycles will be discussed.
Species 1: Diptera Culicidae (mosquitoes)
Keywords: West Nile virus, spatial analysis
The ESA 2001 Annual Meeting - 2001: An Entomological Odyssey of ESA