Delaware Horse Latest Victim of Eastern Equine Encephalitis Diagram © Mayo Foundation for Medical Education & Research

Delaware Horse Latest Victim of Eastern Equine Encephalitis

A yearling filly diagnosed with Eastern Equine Encephalitis was euthanized after failing to respond to treatment, according to Delaware officials. The horse originated in Sussex County.

This is the third Delaware horse this year to be diagnosed with a mosquito-borne disease. Two horses have been diagnosed with West Nile Virus and both recovered. The last case of equine EEE in Delaware was in 2005. There is no treatment for either.

“With the large mosquito population this year, we continue to urge equine owners to have their horses vaccinated and consult with their veterinarians about maintaining a vaccine program,” said State Veterinarian Dr. Heather Hirst, who heads the Department of Agriculture’s Poultry and Animal Health Section.
“Vaccination can increase a horse’s protection against these sometimes fatal diseases. Prevention is still cheaper than care – and far better than having a horse suffer or die.”
Unvaccinated horses are at the greatest risk of developing clinical signs from both Eastern Equine Encephalitis (EEE) and West Nile Virus (WNV), which are spread by mosquitoes and can be fatal. Horses and humans can contract WNV and EEE if bitten by a mosquito carrying the virus, but it is important to note the viruses are not transmitted between horses or from horses to people.
Hirst said horse owners should contact their veterinarian immediately if they suspect their horse may be showing signs of WNV or EEE. Symptoms of EEE in horses include fever (102.5-104.5°F), loss of appetite, head pressing, depression or personality change, wobbling or staggering, weakness, blindness, convulsions, muscle tremors in the head and neck, and hind-limb weakness. These signs are also consistent with WNV, although a fever may or may not be present with WNV.
Prior to 2013, Delaware’s last confirmed equine case of WNV was in 2003.