Horse owners are urged to take precautions after a horse in Knox County tested positive for West Nile Virus.

The Tennessee Department of Agriculture announced Friday that three horses in the state had been diagnosed with viruses that inflect the blood. Another in Davidson County contracted West Nile, and a horse in Bledsoe County tested positive for equine infectious anemia (EIA).

Sick horses cannot pass the virus to people.

“We think about the summer as being bad for biting insects, but the risk carries well into the fall,” State Veterinarian Dr. Charles Hatcher said. “Horse owners need to be vigilant, take preventive measures, and practice good animal husbandry to protect their livestock year-round.”

Mosquitoes are the most common carrier for West Nile Virus. Symptoms in horses may include fever, weakness, loss of appetite, or convulsions. The illness is treatable and the WNV vaccine for equines is particularly effective.

EIA is commonly transmitted through biting insects or sharing needles. Symptoms in horses may include fever, weakness, swelling, loss of appetite, or colic. There is no cure and infected horses must be permanently quarantined or euthanized.

Experts say horse owners should work their veterinarians to establish a vaccine and testing schedule. They also offer these additional tips:

• Avoid co-mingling your horses with other, unfamiliar horses.
• Never share needles, dental, or surgical equipment among different animals.
• Eliminate standing water sources where insects may gather and breed.
• Manage manure and disposal.
• Apply fly sprays and insect repellants as needed.

Human can be infected by West Nile Virus. The Knox County Health Department tests mosquitoes regularly, and if the virus is detected, they schedule spraying in the impacted areas.