What are alphaviruses?

Alphaviruses are viruses that attack the brain. There are three main types: 1) eastern equine encephalomyelitis (EEE); 2) Venezuelan equine encephalomyelitis (VEE); and 3) western equine encephalomyelitis (WEE).

How can someone come into contact with an alphavirus?

Outbreaks of alphaviruses usually occur in the summer. A person can come into contact with an alphavirus by being bit by a mosquito.

Alphaviruses as weapons: Because they are stable during storage and can be made in large amounts, alphaviruses are considered to be easily weaponized. The viruses can be aerosolized and dispersed into the air.

Please note: Just because you come into contact with an alphavirus does not mean you will get sick from it.

What happens if someone gets sick from an alphavirus?

Most infections with these viruses produce a fever, headache and muscle pain. Severe headache, stiff neck, confusion, seizures, coma and possibly even death can occur.

How likely is someone to die from an alphavirus?

EEE, the most serious of the infections, has a high death rate (up to 35 percent). It also has a high rate of causing problems with the brain. VEE and WEE are less likely to cause brain-related symptoms. VEE has a death rate of less than 1 percent; WEE has a death rate of less than 3 percent.

What is the treatment for alphaviruses?

  • Prevention of illness after contact: None
  • Treatment of illness: There is no specific treatment or established cure for alphaviruses. Supportive care (intravenous fluids, medicine to control fever and pain) is the standard treatment.

Are there vaccines for alphaviruses?

There are vaccines available but there have been problems with their success. New vaccines are in development.

What should be done if someone comes into contact with an alphavirus?

If you think that you or someone you know may have come into contact with an alphavirus, contact the local county health department right away. (Visit for a listing of all county health departments in Illinois or check your local phone book.)

If you or someone you know is showing symptoms of an alphavirus, call your health care provider or the Illinois Poison Center right away. The toll-free number for the poison center is 1-800-222-1222.

Where can one get more information about alphaviruses?