Eastern Equine Encephalitis

A Rare But Often Deadly Disease

Eastern equine encephalitis, or EEE, is a rare brain infection. The EEE virus is typically transmitted between birds by swamp mosquitoes and doesn’t affect humans. In some cases, though, a different type of mosquito acts as a bridge between infected birds and uninfected mammals.

Horses can get EEE and they often die from it. Only about seven humans become infected with EEE each year, but the fatality rate in humans is 35 percent. In the United States, most cases of EEE have been reported in Massachusetts, New York, North Carolina and Florida. In Massachusetts, fewer than 100 people have died from EEE over that last 75 years.

More information on EEE is available at the CDC’s website.

What are the Symptoms of EEE?

Symptoms of EEE begin between four and 10 days after a bite from an infected mosquito. They can come on suddenly, and include:

  • Headache
  • High fever
  • Stiff neck
  • Sensitivity to light
  • Muscle weakness or paralysis

In severe cases, EEE can cause disorientation, seizures and coma. Many people who survive this disease have mild to severe brain damage.

How is EEE Diagnosed and Treated?

If you have symptoms of EEE, see your doctor right away. He or she will take samples of your blood or spinal fluid for testing in the lab. Antibiotics are not effective against EEE or other viral diseases, and no antiviral drugs help with this disease. People with EEE may be hospitalized where they can have supportive therapy such as IV fluids and help with breathing.

How Can I Avoid EEE?

The virus that causes EEE can’t be transmitted directly from horses to humans. People get this disease from infected mosquitoes, and the best way to stay safe is to avoid mosquito bites. These steps can help:

  • Keep your yard free of standing water by emptying any rainwater from flowerpots, wading pools, tires and other containers. Mosquitoes breed in standing water.
  • Wear insect repellent whenever you are outside.
  • Use permethrin insecticide on clothing, tents and other gear.
  • Wear long sleeves and pants in areas with large numbers of mosquitoes.

*The content on this website is for informational purposes only and is not medical advice. Please consult a physician regarding your specific medical condition, diagnosis and/or treatment.