Eastern Equine Encephalitis



Eastern equine encephalitis (EEE) is an infection spread by a bite from an infected mosquito. While EEE is rare, it can be serious and in some cases, fatal.
Effect on Encephalitis on the Brain
Swollen brain
Copyright © Nucleus Medical Media, Inc.


EEE is caused by a virus.

Risk Factors

The greatest risk factors for EEE are spending time in areas where mosquitoes are present, such as wetlands and swamps. Another risk factors is failing to use insect repellent.
Risk factors for developing serious symptoms from EEE include:


Most people with EEE do not have any symptoms.
If symptoms do occur, they may appear in 4-10 days and include:
EEE can lead to more serious, life-threatening symptoms of inflammation of the brain, like altered mental status, weakness, numbness, paralysis, seizures, and coma.


Your doctor will ask about your symptoms and medical history. A physical exam will be done. Questions may include:
A blood test or a test of your spinal fluid is commonly used to confirm the diagnosis of EEE.
Imaging tests may include:


Treatment for EEE focuses on supportive care. Severe symptoms require hospitalization, which may include:


To help reduce your chance of EEE:


Centers for Disease Control and Prevention

National Institute of Neurological Disorders and Stroke


Health Canada

Healthy Alberta


Eastern equine encephalitis. Centers for Disease Control and Prevention website. Available at: Updated August 16, 2010. Accessed January 4, 2013.

Eastern equine encephalitis. EBSCO DynaMed website. Available at: Updated July 13, 2012. Accessed January 4, 2013.

Encephalitis: an overview. EBSCO Nursing Reference Center website. Available at: Updated March 9, 2012. Accessed January 4, 2013.

10/1/2013 DynaMed Systematic Literature Surveillance Reimer LJ, Thomsen EK, Tisch DJ, et al. Insecticidal bed nets and filariasis transmission in Papua New Guinea. N Eng J Med. 2013;369(8):745-53.

Revision Information