Frequently Asked Questions

What is eastern equine encephalitis (EEE)?

EEE is a rare disease caused by a virus spread by infected mosquitoes. EEE virus is one of a group of mosquito-transmitted viruses that can cause inflammation of the brain (encephalitis). In the United States, an average of 11 human cases of EEE are reported annually.

How do people get infected with EEE virus?

EEE virus is transmitted through the bite of an infected mosquito. It does not spread through coughing, sneezing, or touching. In a very small number of cases, EEE virus has been spread through organ donation from an infected donor.

Where and when have most cases of EEE occurred?

Most cases of EEE have been reported from Atlantic and Gulf Coast states. Cases have also been reported from the Great Lakes region. EEE disease cases occur primarily from late spring through early fall, but in subtropical endemic areas (e.g., the Gulf States), rare cases can occur in winter.

Who is at risk for infection with EEEV?

Anyone in an area where the virus is circulating can get infected with EEE virus. The risk is highest for people who live, work, or participate in outdoor activities in or around wooded swampy areas in the eastern United States.

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How soon do people get sick after getting bitten by an infected mosquito?

It takes 4 to 10 days after the bite of an infected mosquito to develop symptoms of EEE.

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What are the symptoms of EEE?

Most people who become infected with EEE virus show either no or mild symptoms such as fever. Severe cases of EEE include encephalitis (swelling of the brain) or meningitis (swelling of the membranes that surround the brain and spinal cord) and begin with the sudden onset of fever, chills, headache, and vomiting. The illness may then progress into disorientation, seizures, and coma. Approximately a third of patients who develop encephalitis due to EEE virus die, and many of those who survive have mild to severe brain damage.

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How is EEE diagnosed?

Diagnosis is based on tests of blood or spinal fluid. These tests typically look for antibodies that the body makes against the viral infection.

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What is the treatment for EEE?

There is no specific treatment for EEE. Antibiotics are not effective against viruses, and no effective anti-viral drugs have been discovered. Severe illness is treated by supportive therapy which might include hospitalization, respiratory support, IV fluids, and prevention of other infections.

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How can people reduce the chance of getting infected with EEE virus?

There is no approved vaccine for people or preventive medicine. The best way to prevent EEE is to prevent mosquito bites.

  • Use insect repellent containing DEET, picaridin, IR3535 or oil of lemon eucalyptus.
  • The repellent/insecticide permethrin can be used on clothing to protect through several washes. Always follow the directions on the package.
  • Wear long sleeves and pants when weather permits.
  • Have secure, intact screens on windows and doors to keep mosquitoes out.
  • Eliminate mosquito breeding sites by emptying standing water from flowerpots, buckets, barrels, and other containers. Drill holes in tire swings so water drains out. Keep children’s wading pools empty and on their sides when they aren’t being used.

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What should I do if I think a family member might have EEE?

Consult your healthcare provider for proper diagnosis.

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