Ten equine West Nile Virus cases now confirmed in Colorado


BROOMFIELD, Colo. – A total of 10 equine West Nile Virus cases have been confirmed in eight Colorado counties: Adams (1), Garfield (1), Larimer (1), Mesa (1), Montrose (1), Pueblo (1), Rio Blanco (1), and Weld (3).

In this WNV seasonal occurrence, veterinarians report more of the horses seem to be acutely neurologic with severe symptoms. Four of the horses have been euthanized due to the severity of the clinical signs.

Vaccines in horses have proven to be a very effective prevention tool for WNV, and horses that have been vaccinated in past years do need an annual booster. If a horse has not been vaccinated in previous years, it will need the two-shot vaccination series within a three to four week period.

In addition to vaccinations, as a preventative measure horse owners should also work diligently to reduce mosquito populations and their possible breeding areas where horses are located. Recommendations include removing stagnant water sources, keeping animals inside during the bugs’ feeding times, which are typically early in the morning and evening, and using mosquito repellents.

Any time a horse displays clinical signs consistent with neurologic disease, a complete veterinary examination is warranted. All infectious or contagious equine neurologic diseases are reportable to the Colorado State Veterinarian’s Office.

A comprehensive chart of reportable animal diseases in Colorado can be found on the CDA website at

The Colorado Department of Public Health and Environment has reported 72 human cases to date in 2019. There has been one human fatality reported. They have published data on human West Nile cases, as well as positive mosquito pools, available on the CDPHE WNV website at

Veterinarians and livestock owners contact: Colorado State Veterinarian’s Office, (303) 869-9130.