State confirms 1st 2025 equine case of West Nile virus in Kittson County

ST. PAUL — A laboratory test confirmed the death of a 3-year-old horse in Kittson County earlier in August was due to West Nile virus.

The Minnesota Board of Animal Health reported the equine case was the first confirmed in the state this year, with six more confirmations of the mosquito-borne disease shortly thereafter.

On July 28, a veterinarian examined the unvaccinated Pintabian filly. The animal was eating and drinking but was unable to stand unassisted, according to a news release. Anti-inflammatory medication and steroids were administered, and a blood sample was collected for virus testing.

The filly continued to decline despite treatment and died three days later. The blood sample confirmed West Nile virus on Aug. 11 at North Dakota State University Veterinary Diagnostic Laboratory.

Since Aug. 9, six more horses in Fillmore, Lincoln, Wadena, Mille Lacs and Wabasha counties tested positive for West Nile virus. Four horses died. In all cases, the animals were either unvaccinated or had an unknown vaccination history.

“We’re in prime WNV season,” stated Dr. Heather Damico, senior veterinarian leading the Board’s equine program, in the release. “The types of mosquitos that spread the disease are more active in July and August leading to more cases of the disease.”

West Nile virus is regularly found in the United States and birds serve as the primary host of the disease. The virus circulates between infected birds and mosquitoes. Once infected, the mosquitoes can transmit the virus to horses or people.

Infected horses cannot spread the virus to people or other horses. The virus can cause inflammation of the brain and spinal cord. Infected horses may or may not show neurological symptoms and may recover completely, especially those who have a history of annual vaccination.

“Vaccinate, vaccinate, vaccinate! Keeping your horses up to date with their annual vaccine boosters is the best way to protect them from mosquito-borne diseases,” Damico stated.

“Nearly all the cases we see in Minnesota horses are in unvaccinated or under-vaccinated animals. Vaccinations prevent infection and reduce the impact of WNV in horses if they do get sick.”

In addition to vaccinations, horse owners can reduce environmental risks of mosquito-borne illnesses by reducing mosquito populations:

• Change water in drinking troughs every week
• Mow long grass
• Drain stagnant water puddles
• Remove items mosquitoes use for breeding grounds, like old tires and tin cans
• Place and maintain screens over windows and stable doors
• Use mosquito repellents to protect horses and people from mosquito bites

Non-negative test results for West Nile Virus disease in animals must be reported to the Board of Animal Health. For more information, visit the board's website.

Mosquitoes can transmit West Nile virus to people; potentially leading to serious illness. The Minnesota Department of Health has confirmed 20 cases of West Nile Virus so far this year. Of those 20 cases, two people have died.

Information about the disease in people can be found at the Minnesota Department of Health website.