Last Updated: 10/05/2022
About Western Equine Encephalitis
- Western Equine Encephalitis Fact Sheet
Answers to frequently asked questions about western equine encephalitis.
- Western equine encephalitis is one of several mosquitoborne diseases that has been seen in Minnesota.
- Preventing Mosquitoborne Diseases
Learn how to minimize your risk to western equine encephalitis and other diseases transmitted by mosquitoes.
- There is a vaccine available for horses to prevent western equine encephalitis. Please contact your veterinarian for vaccine recommendations.
Signs and symptoms
- Most people infected with western equine encephalitis virus will have either no symptoms or a very mild illness.
- A small percentage of people, especially infants and elderly people to a lesser extent, may develop encephalitis (inflammation of the brain).
- Approximately 5-15% of these encephalitis cases are fatal, and about 50% of surviving infants will have permanent brain damage.
- Most of the severe human cases begin with a sudden onset of fever, headache, stiff neck, vomiting, and lethargy.
- Within two to four days, the illness may progress into disorientation, irritability, seizures, and coma.
- There is no treatment for WEE other than supportive care until the acute phase of the illness is over.