With warm weather gathering and mosquito season under way, horse owners are being advised to make certain their equids’ vaccinations are current to protect against the threat of two potentially fatal diseases.

Unvaccinated horses suffer severely when infected with either West Nile virus (WNV) and Eastern equine encephalomyelitis (EEE), which are spread by mosquitoes and can be fatal to horses, said Delaware State Veterinarian Heather Hirst, DVM, MS, who heads the Delaware Department of Agriculture’s Poultry and Animal Health Section.

"Vaccination is a simple and cost-effective way of preventing these diseases–far cheaper than treating them," Hirst said. "Horse owners should take full precautions to keep their horses safe, and be on the alert for signs of infection."

Both horses and humans can contract WNV and EEE if bitten by a mosquito carrying the virus, but it is important to note that the viruses cannot be transmitted between horses or from horses to people. The viruses normally exist in a cycle between mosquitoes and birds, but occasionally EEE can be transmitted from mosquitoes to mammals