PULLMAN, Wash. – The Washington Animal Disease Diagnostic Laboratory (WADDL) has confirmed 10 cases of West Nile fever in horses since Aug. 9.

The laboratory in Washington State University’s College of Veterinary Medicine tested 38 horses since Jan. 1 – a number far below its capacity for testing. All 10 cases confirmed positive recently were in unvaccinated horses in Spokane, Lincoln and Pend Oreille counties in Washington and Boundary County in northern Idaho.  All 10 had neurological disease that occurs with West Nile encephalitis characterized by inflammation of the central nervous system.

The cases are unrelated to the equine herpes virus-1 case confirmed by WADDL last week in a hospitalized horse at WSU’s Veterinary Teaching Hospital.  The EHV-1 horse has since been humanely euthanized.

The reason for the spike in West Nile cases is unknown; however, the recent cases are located further north than detections in previous years.  Veterinarians in WADDL are urging horse owners to contact their veterinarians to seek advice on vaccination and how to eliminate mosquitoes where horses are kept.

The laboratory has also developed Frequently Asked Questions about West Nile fever available at: http://waddl.vetmed.wsu.edu/animal-disease-faq/west-nile-virus .



Charlie Powell, WSU College of Veterinary Medicine, 509-335-7073, cpowell@vetmed.wsu.edu