Eastern Equine Encephalitis

Areas Where It Is Commonly Found

Eastern equine encephalitis is found in:

 

In the United States, most cases have been reported from the eastern seaboard states, the Gulf Coast, and some inland midwestern areas.

 

How Is It Transmitted?

The eastern equine encephalitis virus has a complex life cycle involving birds and a specific type of mosquito, Culiseta melanura, that lives in marshes and swamps. These mosquitoes feed only on birds; they do not feed on humans and other mammals. In rare cases, however, the eastern equine encephalitis virus can escape from its marsh habitat in other mosquitoes that feed on both birds and mammals (including horses and humans). These mosquitoes can transmit the eastern equine encephalitis virus to animals and people. After infection, the virus invades the central nervous system, including the spinal cord and brain.

 

Symptoms of Eastern Equine Encephalitis

Eastern equine encephalitis infection can cause a range of illnesses. Most people have no symptoms; others get only a mild flu-like illness with:

 

For people with an eastern equine encephalitis infection of the central nervous system, a sudden fever and severe headache can be followed quickly by seizures and coma. About half of these patients die from the disease. Of those who survive an infection, many suffer permanent brain damage and require lifetime institutional care.

 

Eastern equine encephalitis symptoms usually appear 4 to 10 days after the bite of an infected mosquito.