Analyses of relationships of human West Nile virus, confined livestock operations, and playa lakes in the Texas Panhandle and South Plains region

A total of 432 human West Nile virus (WNV) cases have occurred with 28 fatalities in the Panhandle and South Plains region from 2002 to 2008 in 41 counties. Of significant interest was determining if these WNV cases were spatially clustered near major ecological and economic features of playa lakes and confined livestock operations (CLOs). Another research interest was to identify chemicals used in mosquito control in regional cities to determine if mosquito control increased during the years of the initial WNV outbreak in the region. An important role of spatial statistics is to account for spatial dependence and search for spatial patterns in geographical data. Cluster investigations have long been an important tool in epidemiology and spatial statistics. To quantify WNV prevalence in the region for clustering around CLOs and playa lakes, SaTScan™ and ArcGIS™ were used in conjunction to determine spatial clustering. Spatial clustering results indicate that a spatial correlation and dependence exists in the geographical data between human WNV cases, beef cattle operations and playa lakes. Malathion was identified as the most common pesticide used in the region from 2002 – 2009.