Triple E Virus Deadly to Horses and Humans

By Justin Miller

Summer brings a heightened risk of mosquito borne illnesses. Eastern equine encephalitis is one of the most deadly. Known as EEE or sleeping sickness and commonly associated with horses, only a few human cases are reported in the United States annually.  But according to the Centers for Disease Control, EEE ranks as one of the most severe mosquito-transmitted diseases with approximately 33 percent mortality in people.

Recently, the Alabama Department of Agriculture & Industries announced a Georgia horse tested positive for EEE after it was brought to Auburn University’s College of Veterinary Medicine. In addition, the Mobile County Health Department identified EEE in sentinel chicken flocks used to monitor for such diseases. The health department tests blood samples from the flocks for the presence of EEE and other mosquito borne illnesses such as West Nile virus.

While there is no vaccine for humans, there is little reason for a horse to contract the disease because a safe and inexpensive vaccine is available. Dr. Courteney Holland, an Alabama Extension animal scientist, says horse owners should remember to vaccinate their animals every year.

“Horse owners should vaccinate their horses twice a year for sleeping sickness,” said Holland. “Revaccinate in mid- to late-summer, such as August or September.”
A viral disease spread by certain kinds of mosquitoes, EEE is almost always fatal in horses. Characterized by the progressive failure of the horse’s central nervous system, symptoms include depression, high fever, hypersensitivity to sound and touch, apparent blindness, wandering and paralysis. The horse is a terminal host for the virus and cannot spread the disease to humans or other animals.

There is not much an owner can do once their horse develops EEE. The mortality rate is 75 to 100 percent. Holland said if they do survive, they will show gradual improvement of function over weeks to months but the horse may never recover fully.
“Horses may have permanent brain damage,” said Holland. “Vets usually recommend to put the horses down because of the neurological damage.
Reduce Exposure

To reduce exposure to mosquitoes for both humans and horses, eliminate the breeding grounds for mosquitoes. Mosquitoes can breed in any source of water that lasts more than four days.) Do not allow buckets, wheel barrows, old tires and watering troughs to collect water. Store these items in a barn or garage.  If left outside, turn them over so they do not collect water. For watering troughs, be sure to empty out the water every few days to help reduce the risk. Another control measure is using insect repellents on yourself and horses. This may help slow the spread of the disease. Horse owners may want to stable their animals to limit their exposure to mosquitoes.  Turn stable lights off at night to reduce the number of insects attracted to the facility.

Source: aces.edu