Development of a Sampling Scheme for West Nile Virus Testing in Urban and Rural Environments

Abstract

A sampling scheme has been developed for West Nile Virus (WNV) testing in urban and rural environments for four study sites proximal to cities in Mississippi that are representative of a wide variety of ecological conditions. Population clustering and landscape characteristics were taken into consideration for a development of sample stratification scheme that minimizes redundancy for testing for WNV in bird and mosquito populations. The stratification scheme divides census block groups into rural and urban polygons and characterizes similar landscape conditions associated within these polygons. Landform characteristics for water percentage and terrain roughness were measured for these polygons using a GIS zonal statistics function and classified into three categories of roughness and three categories of percent water. Combination of these categories resulted in nine unique index values that provide a simple measure of landscape characteristics. Locating similar index values for urban and rural polygons enables matching of sample sites with similar landscape properties for all four study sites. The implementation of this sample design for testing birds and mosquitoes is important for determining whether WNV disease repository originates in urban environments and spreads to rural areas or vice versa.