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
EEE is caused by a virus.
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:
- Being over 50 years old or younger than 15 years old
- Having a condition that affects your immune system
Most people with EEE do not have any symptoms.
If symptoms do occur, they may appear in 4-10 days and include:
- Neck stiffness
- Joint and muscle pain
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:
- Where you have been living or traveling
- Whether you have been exposed to mosquitoes
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:
- Mechanical ventilation (breathing support)
- IV fluids
- Medication to control seizures
- Medication to decrease brain swelling
To help reduce your chance of EEE:
- Stay inside when mosquitoes are most active (at dawn and at dusk).
- Repair screens on your windows and doors to prevent mosquitoes from getting into your house.
- Use proper mosquito netting at night. Look for netting treated with insecticide.
- When outside, wear insect repellent, long pants and long-sleeved shirts to limit exposure to bites.
- Eliminate insect breeding areas. These may include areas of standing water, like pet water bowls, rain barrels, and other containers.
Centers for Disease Control and Prevention
National Institute of Neurological Disorders and Stroke
Eastern equine encephalitis. Centers for Disease Control and Prevention website. Available at: http://www.cdc.gov/easternequineencephalitis. Updated August 16, 2010. Accessed January 4, 2013.
Eastern equine encephalitis. EBSCO DynaMed website. Available at: http://www.ebscohost.com/dynamed. Updated July 13, 2012. Accessed January 4, 2013.
Encephalitis: an overview. EBSCO Nursing Reference Center website. Available at: http://www.ebscohost.com/nursing/products/nursing-reference-center. Updated March 9, 2012. Accessed January 4, 2013.
10/1/2013 DynaMed Systematic Literature Surveillance http://www.ebscohost.com/dynamed: Reimer LJ, Thomsen EK, Tisch DJ, et al. Insecticidal bed nets and filariasis transmission in Papua New Guinea. N Eng J Med. 2013 Aug 22; 369(8):745-53.
Last reviewed December 2014 by David L. Horn, MD, FACP
Please be aware that this information is provided to supplement the care provided by your physician. It is neither intended nor implied to be a substitute for professional medical advice. CALL YOUR HEALTHCARE PROVIDER IMMEDIATELY IF YOU THINK YOU MAY HAVE A MEDICAL EMERGENCY. Always seek the advice of your physician or other qualified health provider prior to starting any new treatment or with any questions you may have regarding a medical condition.