Officials in Florida have reported the 20th case of Eastern Equine Encephalitis (EEE) in a horse in 2016. The 11 year old Quarter Horse mare from Sumter County was last vaccinated for EEE in late Summer 2015 per the owner and had no recent travel history.


Clinical signs began on August 13 and the horse was euthanized for humane reasons later the same day.

EEE causes inflammation of the brain tissue and has a significantly higher risk of death in horses than West Nile Virus infection. West Nile virus is a viral disease that affects horses’ neurological system. The disease is transmitted by mosquito bite. The virus cycles between birds and mosquitoes with horses and humans being incidental hosts. EEE infections in horses are not a significant risk factor for human infection because horses (like humans) are considered to be “dead-end” hosts for the virus.

Effective equine vaccines for EEE and WNV are available commercially. Horse owners should contact their veterinarians if their horses are not already up-to-date on their vaccinations against both EEE and WNV.