State officials are warning of the dangers of West Nile virus after confirming the first case of equine West Nile virus of 2023 in a gelding in Weld County.
The horse was euthanized, as it presented with sudden neurological symptoms including weakness, stumbling and recumbency, according to the state. The gelding’s age and vaccine status are unknown.
The state’s announcement, issued Friday, comes one day after Weld County officials announced health officials are investigating the county’s first potential human case of West Nile of the 2023 season. The county did not disclose details about the patient’s condition.
West Nile occurs in both humans and animals. The first human case in the state this year was confirmed by the state health department on July 24 in La Plata County. Mosquito pools from Arapahoe, Boulder, Delta, Denver, Larimer, Pueblo and Weld counties have tested positive for the virus this summer, according to the state.
Weld officials reported mosquitoes have tested positive from all three zones monitored across the county. Weld, as well as Larimer and Boulder counties, has seen especially high activity, according to the state.
Officials say the heavy snowpack this past winter, a wet spring and warmer temperatures have led to increased mosquito activity.
“The positive human case, equine case and mosquito pools are a reminder that West Nile Virus is actively circulating in Colorado and continues to pose a risk to people and unvaccinated equines,” Colorado State Veterinarian Maggie Baldwin said in a news release. “Horse owners should work with their veterinarians to determine the appropriate vaccination schedule to keep their animals healthy.”
The virus cycles between wild birds and mosquitoes and can sometimes affect other species including people and equines. Clinical cases in horses can include weight loss, depression, muscle weakness or paralysis of one or more limbs, teeth grinding, aimless wandering, convulsions and circling.
Most people infected with West Nile don’t show any symptoms but may develop symptoms including fever, headache, rash, nausea and muscle aches. Less than 1% of patients develop a serious illness affecting the nervous system that can be fatal. Any person who develops symptoms should see a health care professional immediately.
Though there is no vaccine nor medicine to treat West Nile in people, vaccines are a safe and effective prevention tool available to horses. Horses that have not been vaccinated require a two-shot vaccination series, and those that have been vaccinated require an annual booster, according to the state.
Horse owners and residents alike are encouraged to reduce mosquito populations and their possible breeding areas by removing stagnant water sources, using mosquito repellents and keeping animals and people inside during mosquitoes’ feeding times, typically early in the morning and evening.
The state says a complete veterinary examination is warranted any time a horse displays signs of a neurologic disease. All infectious or contagious equine neurologic diseases are reportable to the Colorado State Veterinarian’s Office at (303) 869-9130.
