Eastern equine encephalomyelitis, also called Triple E or Sleeping Sickness, is a zoonotic arbovirus present in the Caribbean as well as in the South, Central and North America. Eastern equine encephalomyelitis can infect various animals, including amphibians, birds, mammals and reptile, but is more common in horses.

Eastern equine encephalomyelitis can be prevented in horses through vaccinations. However, there is no known treatment for the disease once it has infected an animal. Mortality rates for horses is at 70 to 90 percent.

Symptoms of Eastern equine encephalomyelitis start to show in one to three weeks with fever up to 106 degrees Fahrenheit, lasting only up to 48 hours. Nervousness, sensitivity to sound, restlessness and a sudden period of excitement can also be present during the fever. When brain lesions appear, it causes abnormal gait, drooping ears and drowsiness. Horses usually experience paralysis and death within two to four days after the first signs of the disease appear.

The virus named after this disease (Eastern equine encephalomyelitis virus or EEE) causes eastern equine encephalomyelitis. The hosts are mosquitoes that feed on the blood of birds and other animals.