Equine West Nile virus positives diagnosed in December, Texas cases total 38


TVMDLTypically, West Nile virus (WNV) cases are not diagnosed into December; however, this year suspicious specimens were sent to the Texas A&M Veterinary Medical Diagnostic Laboratory (TVMDL) into December.

It is expected that WNV cases will drop off as the weather across the state cools and the environment for the mosquitoes that are the vector for the disease diminishes.


As of December 18, 2015, TVMDL can confirm horses in the following counties tested positive for WNV in 2015.

1.   Houston County

2.   Atascosa County

3.   Jefferson County (4 cases)

4.   Roberts County

5.   Sterling County

6.   Parker County

7.   Randall County

8.   Liberty County

9.   Scurry County

10. Hutchinson County

11. Taylor County

12. Nolan County

13. Trinity County

14. Robertson County (2 cases)

15. Midland County

16. Orange County

17. Harris County (3 cases)

18. Victoria County

19. Cooke County

20. Chambers County (2 cases)

21. Erath County

22. Freestone County

23. Smith County

24. Nueces County

25. Collin County

26. Wichita County

27. Lavaca County

28. Jackson County

29. Angelina County

"The number of West Nile virus cases we have seen in 2015 points out the risk to our equine population and the importance of vaccination," said TVMDL Assistant Director Terry Hensley, MS, DVM. "The horses represented in these cases were either unvaccinated or had lapsed in their vaccinations. The majority of the horses exhibited classical neurological signs which indicates the importance of diagnostic testing as an aid in confirming a clinical diagnosis."

This year's positive case map dispels the general public's belief that WNV is only a threat in low-lying or coastal areas, as positive cases were found from the Panhandle to Dallas, to South Texas and the Houston area. The most prolific area with positive cases was the southeastern region of the state.

Symptoms for other neurologic diseases can present similarly; diagnostic testing is the only method to definitively determine infection. In order to have a complete diagnostic picture, TVMDL also recommends veterinarians request additional tests including: Equine Herpesvirus-1, Eastern Equine Encephalitis (EEE) and Western Equine Encephalitis. In 2015, TVMDL confirmed four positive cases of EEE in southeast Texas.

The Texas Department of State Health Services and the Texas Animal Health Commission have information related to WNV and mosquito control available for free download.

For more information on TVMDL's equine neurologic testing, visittvmdl.tamu.edu, or contact the agency headquarters at 1.888.646.5623.

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