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Press Releases

June 26, 2018
Reminder from the State Veterinarian: with 2018’s Strong Mosquito Season, Horse Owners Need to Vaccinate Most Horses Now against Mosquito-borne Diseases
Contact: Elaine Lidholm, 804.786.7686

Mosquito season 2018 is a strong one, one of the worst in years. The deluge of rain has created stagnant pools of water perfect for mosquito breeding while cooler temperatures have helped to slow the maturation of larvae, delaying the pests’ season this year. “Now it has hit in full force, and horses are at risk of contracting mosquito-borne diseases such as Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV),” said Dr. Charles Broaddus, State Veterinarian with the Virginia Department of Agriculture and Consumer Services (VDACS).

The mortality rate with WNV is 30 percent, but up to 90 percent with EEE. There is no proven cure for these diseases, but veterinarians can provide supportive therapy.  

VDACS recommends that horse owners check with their veterinarians and if she or he recommends vaccination, the time to do it is now. “Both the WNV and EEE vaccine are highly effective in minimizing disease, if given appropriately,” said Dr. Broaddus. The vaccines are effective for 6-12 months, so most owners revaccinate at least annually and in areas where the disease occurs frequently, every six months. For the vaccine to be effective, it must be given at least two weeks before the horse is exposed to the virus. To stimulate full immunity, horses must be vaccinated twice, about 30 days apart, the first year of vaccination.

Other prevention methods include dumping or draining standing water breeding sites (containers and puddles) for mosquitoes, using insect repellents and removing animals from mosquito-infested areas during peak biting times, usually dusk to dawn, and turning off the lights in and around the barn at night.

Humans cannot become infected with EEE or WNV by handling an infected horse, nor can a horse acquire the virus directly from another infected horse. The presence of an infected horse in the area indicates that mosquitoes carrying the EEE or WNV viruses are present, however, and those insects pose a threat to both humans and horses.

Click here for more information on WNV and EEE, or contact the VDACS Office of Veterinary Services at 804.786.2483.

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