Officials confirm first two cases of West Nile Virus in Del. horses

DELAWARE – The Office of the State Veterinarian confirmed, on Thursday, Delaware’s first two cases of West Nile Virus (WNV) in horses for the year 2018.

The first infected horse is a 3-year-old Standardbred mare in Kent County. The horse reportedly began showing signs of wobbling and staggering on August 19. Samples were submitted to the National Veterinary Services Laboratory, which confirmed the diagnosis of WNV on August 24. No vaccination history was available for the horse. The horse has shown slight improvement in its health.

The second infected horse is a 2-year-old Thoroughbred mare, also in Kent County. This horse was evaluated by a veterinarian on August 25. The vet says the horse had a fever, mild wobbling and staggering, droopy eyelid, difficulty controlling muscles of the mouth and throat, as well as depression. Cornell University Animal Health Diagnostic Center tested samples and confirmed WNV infection on August 28. This horse was not up-to-date on its WNV vaccine. The attending veterinarian has not reported any improvement in this horse’s condition.

Officials say West Nile Virus and Eastern Equine Encephalitis (EEE) are diseases transmitted to horses through mosquito bites. Humans can also be infected with WNV and EEE, but only though a mosquito bite. Health officials say the virus cannot be directly transmitted between horses, or between horses and people.

Signs of infection in horses include fever, anorexia, head pressing, depression or personality change, wobbling or staggering, weakness, blindness, convulsions, muscle spasms in the head and neck, or hind-limb weakness. If owners notice any of these signs in their horses, they should contact their veterinarian immediately.

Two cases of WNV were confirmed in Delaware horses in 2017. So far in Delaware in 2018, two cases of WNV have been found in humans.

The State Veterinarian urges horse owners to contact their veterinarians as soon as possible, because Delaware is in the midst of peak mosquito season. Experts also say residents should have horses and other equines vaccinated against WNV and EEE. Neither disease has a specific drug treatment, and EEE infections in horses are fatal in 70 to 90 percent of cases, and WNV in 30 percent of cases.

For more information about WNV or EEE:

  • Human health questions should be directed to the Delaware Division of Public Health, (888) 295-5156, or (302) 744-4990.
  • Animal health questions should be directed to the Delaware Department of Agriculture at (800) 282-8685 (Delaware only) or (302) 698-4500. Ask for the Poultry and Animal Health Section.
  • Questions about the state’s mosquito control program or mosquito biology should be directed to the Delaware Department of Natural Resources and Environmental Control’s Mosquito Control Section at (302) 739-9917.
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