The Virginia Department of Agriculture and Consumer Services (VDACS)  announced on July 10, 2017 the state’s first positive case of West Nile Virus (WNV) in a horse in 2017. It is the first case since August 2015 in Virginia. The horse, a ten-year-old Saddlebred gelding, was from Wythe County and died as a result of the disease. Symptoms included loss of control of bodily movements and partial paralysis in the hind limbs, dazed appearance and lack of ability to stand.

The horse was euthanized because of the severity of his symptoms and necropsied at VDACS’ Regional Animal Health Laboratory (RAHL) in Wytheville and tested positive on June 29 at the Warrenton RAHL via a serologic test. The positive was confirmed at the National Veterinary Service Laboratories Friday July 7. It had not been vaccinated.

Dr. Joe Garvin, head of VDACS’ Office of Laboratory Services, urges horse owners to check with their veterinarians about vaccinating their animals for WNV. “West Nile is a mosquito-borne disease,” he said, “and we generally start seeing our first cases in August and September. The disease is usually preventable by vaccination, as is Eastern Equine Encephalitis, so many veterinarians recommend vaccination at least yearly, and in mosquito-prone areas, every six months.” He adds that mosquito season in Virginia can run through November.

The WNV vaccine for equines initially requires two doses administered three to six weeks apart. The vaccine takes four to six weeks from the second dose for optimal effectiveness. Horse owners should consult with their veterinarians to choose a re-vaccination schedule to protect their horses effectively.

Prevention methods besides vaccination include destroying standing water breeding sites for mosquitoes, use of insect repellents and removing animals from mosquito-infested areas during peak biting times, usually dusk to dawn. Continuous, effective mosquito control can minimize the risk of exposure of both horses and humans to mosquito-borne diseases.

Currently, no drugs exist to treat WNV specifically in horses or humans. The mortality rate in equines with WNV is about 30 percent. Since there is no specific treatment for WNV, treatment consists of supportive therapy to maintain the animal’s hydration and to prevent the animal from injuring itself. A veterinarian can prescribe treatment tailored to the particular case.

Equine owners should consult their veterinarians if an animal exhibits any neurological symptoms such as a stumbling gait, going down, facial paralysis, drooping or disinterest in their surroundings.

The following websites provide more information on WNV and how to protect humans and horses:

Horses:
Virginia Department of Agriculture and Consumer Services, West Nile Virus information page

Humans:
Virginia Department of Health, West Nile Virus information
Centers for Disease Control, West Nile Virus information