Eastern Equine Encephalitis

Eastern Equine Encephalitis

Public Health Fact Sheet

What is Eastern Equine Encephalitis (EEE)?
EEE is a rare, but serious disease caused by a virus spread by infected mosquitos.  EEE affects humans and horses. The EEE virus can cause encephalitis or swelling of the brain.  Approximately one-third of the human cases are fatal.

How is Eastern Equine Encephalitis spread?
The virus that causes the disease lives almost exclusively in the bloodstream of infected birds, and in the mosquitoes that bite those birds. Once bitten by an infected mosquito, humans usually become sick 4-10 days later.

How is EEE treated?
There is no cure or specific treatment for EEE.  The treatment is supportive only.  Death usually occurs 2 - 10 days after onset of symptoms but can occur much later.  Of those who recover, many are left with disabling and progressive ,mental and physical sequelae, which can range from minimal brain dysfunction to severe intellectual impairment, personality disorders, seizures, paralysis, and cranial nerve dysfunction.  Many patients with severe sequelae die within a few years. 

How is EEE prevented?
  • Use insect repellent. Repellents containing 20-30% DEET work best. Limit outdoor activity in the evening, when mosquitoes are most active.
  • Maintain window and door screens to keep mosquitoes out. Reduce mosquito populations by eliminating all standing water that collects in birdbaths, boats, buckets, tires, unused pools, roof gutters, etc.
  • Avoid shaded areas where mosquitoes may be resting.
  • Wear protective clothing such as long-sleeved shirts and pants.
Additional information is available on the CDC website at www.cdc.gov/easternequineencephalitis/  

Symptoms of Eastern Equine Encephalitis (EEE)
  • Abrupt onset of fever
  • Headache
  • Body aching
  • Disorientation
  • Change in level of consciousness
  • Varying paralysis
  • Coma
  • Death

February 2020