| dc.description.abstract | West Nile Virus (WNV) first appeared in Texas equids during June 2002. It has
since spread rapidly across the state and apparently become endemic. Data from
outbreaks occurring between 2002 and 2004 were analyzed to determine hotspots of
equine WNV disease, identify environmental factors associated with outbreaks, and to
create risk maps of locations with horses at a higher risk of the disease. Kriging was used
to model the smoothed WNV attack rates, and interpolated rates were mapped to describe
the spatial distribution of WNV disease risk in Texas. A retrospective time-space
analysis using a Poisson model was conducted on each year’s data to identify clusters
with high attack rates. The resulting overlapping yearly clusters were considered areas of
hyperendemicity (hotspots). The counties identified as hotspots included Hockley,
Lubbock, and Lynn (primary cluster) and Leon and Roberstson (secondary cluster).
Environmental and geographic features were added to the disease maps and analyzed to
determine possible environmental factors associated with outbreaks. Locations in close
proximity to lakes, bird breeding routes, migratory flyway zones, crop farm and
agricultural land, and all dense vegetation were found to be important environmental predictors. Finally, risk maps were created that combined surveillance data on WNV
positive mosquito collections and wild bird WNV cases with previously identified
environmental risk factors to predict areas of high occurrence of WNV. These risk maps
could be used to implement various preventative measures to reduce the transmission of
WNV in the Texas equine industry. | en |
