Avoid mosquito-borne viruses

— Written By and last updated by


by Tiffanee Boone

Warm, wet conditions are optimal for mosquitoes to thrive. Not only you, but also your horses need protection. Equines are susceptible to several virus-borne diseases, including West Nile Virus (WNV) and Eastern Equine Encephalomyelitis (EEE). More than 15,000 horses have contracted West Nile Virus since it was first detected in the United States in 1999. Approximately one-third of those horses diagnosed with the virus died or were euthanized. Symptoms of WNV in horses can include loss of appetite, depression, fever, weakness or paralysis of hind limbs, convulsions, impaired vision or hyper-excitability. Symptoms of EEE, which is also known as “equine sleeping sickness,” include impaired vision, aimless wandering, head pressing, circling, inability to swallow, irregular staggering gait, paralysis, convulsions and death.

Vaccinations and boosters prevent horses, donkeys and mules from getting these deadly diseases. Horses that are vaccinated and receive boosters at the designated intervals have the highest level of protection against the mosquito-borne viruses. They should be vaccinated before the peak mosquito season. The vaccine requires two doses, given two to three weeks apart. Full protection does not develop until four to six weeks after the second dose. It can take up to 10 weeks for a horse to be disease-resistant. Horse owners should talk with their veterinarians to determine the best time to start the vaccination process for EEE and WNV. The vets can also schedule subsequent boosters for ongoing protection.

Combination products are available to protect equines from multiple diseases to
reduce the number of injection sites and provide a better cost:benefit ratio for the owner. One combination vaccine, for example, protects against WNV, EEE and tetanus.

Humans, horses, and birds can get infected by a mosquito carrying a virus, but no evidence shows that horses can transmit the virus to other horses, birds, or people through direct contact. WNV has occasionally been reported from ticks, mostly from bird-feeding ones. Studies have shown that normally only a small percentage of humans infected with the virus will show symptoms of the disease. The symptoms of West Nile Virus in humans include fever, rash, headache, backache, fatigue, meningitis, nausea, coma and death.

To protect yourself and your family, you can avoid shaded areas where mosquitoes may be resting, limit evening outdoor activity when mosquitoes are most active, wear protective clothing such as long-sleeved shirts and pants, and use insect repellents that contain DEET or picaridin. Never use repellents on infants. As with all products, follow the label. You can also reduce mosquito populations on your property by removing the larval habitat: stagnant water that collects in unused pools, boats, buckets, tires, roof gutters, and other containers. Also empty and refill birdbaths and pet bowls every 3 – 4 days. Make sure that outdoor faucets are not leaking, and fill in potholes and other areas that may collect water.

Reducing the mosquito population, vaccinating equines and applying mosquito repellents on people will minimize the risk of mosquito-borne viral diseases.

For additional information about mosquito-born diseases or other livestock issues,
please contact Anthony Growe, Livestock Extension Agent at 910-997-8255 or amgrowe@ncsu.edu. Check out our webpage at N.C. Cooperative Extension Richmond County Center.