What Are the Symptoms of Eastern Equine Encephalitis?

Medically Reviewed on 12/1/2021
What Are the Symptoms of Eastern Equine Encephalitis
Eastern equine encephalitis is a rare, serious disease that is spread by infected mosquitoes. Symptoms include fever, chills, joint pain, and body aches

Eastern equine encephalitis (EEE) is a rare but serious disease that is spread by infected mosquitoes and causes inflammation of the brain. Most cases are recorded in the United States during the late summer and early fall months. 

Although most people infected with the EEE virus are asymptomatic, some present with mild symptoms for about 1-2 weeks. Symptoms may include:

Approximately 5% of people who are bitten by an infected mosquito will develop a complicated form of eastern equine encephalitis and about 30% of the cases succumb to death.

What are complications of eastern equine encephalitis?

While anyone can develop complicated EEE, children under 15 years old and adults over 50 years old are at the greatest risk for complications. These complications include:

  • Encephalitis (swelling of the brain): Symptoms include high fever, vomiting, headache, personality changes, drowsiness, convulsions, abnormal movements of limbs, and coma.
  • Meningitis (swelling of the membranes covering the spinal cord and brain): Symptoms include high fever, headache, photosensitivity (intolerance to light), and vomiting. Some progress to disorientation, irritability, seizures, and coma.
  • Long-term sequelae in survivors: About a third of patients who develop EEE die, whereas some who survive have mild to severe brain damage, which manifests as persistent headaches, memory impairment, tremors, cranial nerve involvement, depression, and paralysis of limbs.

How is eastern equine encephalitis treated?

Unfortunately, there are currently no vaccines or antiviral medications to prevent or treat eastern equine encephalitis. Most patients with mild symptoms are advised to rest and hydrate. Acetaminophen may be taken for fever and ibuprofen for body aches. 

Those with a complicated form of the disease must be admitted to intensive care, where symptoms are managed with intravenous hydration and medications to reduce brain edema. Patients are also screened and treated for breathing, electrolyte imbalances, and seizures.

How can you prevent eastern equine encephalitis?

The only way to prevent EEE infection is to prevent mosquito bites. This can be accomplished with methods that include the following


When outdoors, always wear long-sleeved shirts and pants and closed footwear that covers the feet and ankles

Environmental Protection Agency-approved insect repellents

These repellents include N, N-diethyl-meta-toluamide, picaridin, lemon eucalyptus oil, para-menthane-diol, and 2-undecanone, which can be applied to the clothes or over the skin when outdoors. These are safe for kids as well as pregnant and breastfeeding women when used according to the directions on the package.

Exercise caution when using the insect repellents:

  • Never apply over cuts, wounds, or irritated skin.
  • Never spray on a child’s hands, eyes, or mouth.
  • Para-menthane-diol and lemon eucalyptus oil are only advised for use on kids over the age of 3.
  • Adults must spray the repellent on their own hands and then apply it on a child’s face.

Mosquito screens

Fix mosquito screens on windows and doors. Make sure that there are no holes in the screens. In hotels, opt for rooms with air conditioning. Sleep inside a mosquito net whenever possible. Use mosquito nets to cover strollers and baby carriers.

Mosquito control

To stop mosquitoes from laying eggs in or near water, clear out stagnant water sources in or near the house. These sources include water vases, potted plants, tires, buckets, planters, toys, pools, birdbaths, flower pots, and trash containers. Spray these areas once a week with insect repellents.


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Medically Reviewed on 12/1/2021
Image Source: iStock Images

Centers for Disease Control and Prevention. Eastern Equine Encephalitis (EEE). https://www.cdc.gov/easternequineencephalitis/index.html

Raven K. Eastern Equine Encephalitis (EEE) is Back—Should You Be Worried? Yale Medicine. https://www.yalemedicine.org/news/eastern-equine-encephalitis