Identification of hyperendemic foci of horses with West Nile virus disease in Texas.
OBJECTIVE
To determine whether West Nile virus (WNV) disease hyperendemic foci (hot spots) exist within the horse population in Texas and, if detected, to identify the locations.


METHODS
Reports of 1,907 horses with WNV disease in Texas from 2002 to 2004.


METHODS
Case data with spatial information from WNV epidemics occurring in 2002 (1,377 horses), 2003 (396 horses), and 2004 (134 horses) were analyzed by use of the spatial scan statistic (Poisson model) and kriging of empirical Bayes smoothed county attack rates to determine locations of horses with WNV disease in which affected horses were consistently (in each of the 3 study years) clustered (hyperendemic foci, or hot spots).


RESULTS
2 WNV hot spots in Texas, an area in northwestern Texas and an area in eastern Texas, were identified with the scan statistic. Risk maps of the WNV epidemics were qualitatively consistent with the hot spots identified.


CONCLUSIONS
WNV hot spots existed within the horse population in Texas (2002 to 2004). Knowledge of disease hot spots allows disease control and prevention programs to be made more efficient through targeted surveillance and education.
Wittich
Courtney A
CA
Department of Veterinary Integrative Biosciences, College of Veterinary Medicine and Biomedical Sciences, Texas A&M University, College Station, TX 77843-4458, USA.
Ward
Michael P
MP
Fosgate
Geoffrey T
GT
Srinivasan
Raghavan
R
D000818:Animals; D016000:Cluster Analysis; D004196:Disease Outbreaks / Q000662:veterinary*; D006734:Horse Diseases / Q000453:epidemiology* / Q000821:virology*; D006736:Horses; D012621:Seasons; D013781:Texas / Q000453:epidemiology; D014901:West Nile Fever / Q000453:epidemiology / Q000662:veterinary* / Q000821:virology; D014902:West Nile virus / Q000254:growth & development*