Eastern Equine Encephalitis
Eastern Equine Encephalitis (EEE) is carried by certain types of mosquitoes in Michigan. It is a potentially serious disease that can affect anyone, but children and people over age 60 are more likely to get the more severe form of EEE illness. EEE is found primarily in areas with swamps and bogs. The risk of bites from infected mosquitoes is highest for people who work or play outdoors in these areas. Wearing insect repellent when outdoors (especially at dawn and dusk) is important to prevent EEE.
EEE is also a serious disease in horses. Protecting horses with approved EEE vaccines is an important prevention measure.
Eastern Equine Encephalitis Virus Activity in Michigan
(as of August 16, 2019):Click the links below to view the cases in the Michigan Disease Mapper.
Who is at risk?
Who is at risk of Eastern Equine Encephalitis (EEE) illness?
People who engage in outdoor work and recreational activities in endemic areas are at increased risk of infection. Persons over age 50 and under age 15 seem to be at greatest risk for developing severe disease when infected with EEE. Overall, only about 4-5% of human EEE infections result in EEE illness. EEE infection is thought to confer life-long immunity against re-infection.
Where is EEE a risk in Michigan?
EEE has been reported in animals and people throughout the state. EEE is most commonly found in swamp and bog habitats. All residents of and visitors to areas where EEE activity has been identified are at risk of infection.
Signs and Symptoms
What are the symptoms of Eastern Equine Encephalitis (EEE) infection?
No symptoms in many people. Most people who become infected with EEE do not develop any symptoms.
Febrile illness in some people. Only 4-5% of people will be become sick when infected with EEE. Some people who are infected will develop chills, fever, weakness, muscle and joint pain. The illness may last up to two weeks. Most people with this type of EEE disease recover completely, but fatigue and weakness can last for weeks or months.
Severe symptoms in a few people. Less than 1% of people who are infected will develop a serious neurologic illness such as encephalitis or meningitis (inflammation of the brain or surrounding tissues).
- The symptoms of neurologic illness can include high fever, headache, irritability, restlessness, drowsiness, anorexia, vomiting, diarrhea, bluish discoloration of the skin, convulsions, and coma.
- Serious illness can occur in people of any age. However, children and people over 60 years of age are at the greatest risk for severe disease. People with certain medical conditions, such as cancer, diabetes, hypertension, kidney disease, and people who have received organ transplants, are also at greater risk for serious illness.
- Recovery from severe disease may take several weeks or months. Of those who recover, many are left with disabling and progressive mental and physical sequelae, which include can range from minimal brain dysfunction to severe intellectual impairment, personality disorders, seizures, paralysis, and cranial nerve dysfunction. Many patients with severe sequelae die within a few years.
- About 30 percent of people who develop neurologic infection due to Eastern Equine Encephalitis will die.
Diagnosis and Testing
What should I do if I think a family member might have Eastern Equine Encephalitis?
Consult a healthcare provider for evaluation and diagnosis.How is Eastern Equine Encephalitis diagnosed?
Diagnosis is based on a combination of clinical signs and symptoms and specialized laboratory tests of blood or spinal fluid. These tests typically detect antibodies that the immune system makes against the viral infection.Important Links
- Laboratory Testing
- Case Reporting
- Specimen Collection and Submission
Treatment
How is Eastern Equine Encephalitis (EEE) treated?
No human vaccine against EEE infection or specific antiviral treatment for clinical EEEV infections is available. Patients with suspected EEE should be immediately evaluated by a healthcare provider, appropriate serologic and other diagnostic tests ordered, and supportive treatment provided.
Prevention
How do I protect myself and my family from Eastern Equine Encephalitis (EEE)?
There is no vaccine against EEE virus for humans. Reducing exposure to mosquitoes is the best defense against infection with EEE and other mosquito-borne viruses. There are several approaches you and your family can use to prevent and control mosquito-borne diseases.
- Use repellent: When outdoors, use insect repellent containing DEET, picaridin, IR3535 or oil of lemon eucalyptus on exposed skin and/or clothing. The repellent/insecticide permethrin can be used on clothing to protect through several washes. Always follow the directions on the package.
- Wear protective clothing: Wear long sleeves and pants when weather permits.
- Install and repair screens: Have secure, intact screens on windows and doors to keep mosquitoes out.
- Keep mosquitoes from laying eggs near you: Mosquitoes can lay eggs even in small amounts of standing water. Get rid of mosquito breeding sites by emptying standing water from flower pots, buckets, barrels, and tires. Change the water in pet dishes and replace the water in bird baths weekly. Drill holes in tire swings so water drains out. Empty children's wading pools and store on their side after use.
How do I protect my horse(s) from Eastern Equine Encephalitis (EEE)?Vaccines are available for horses that will protect them from EEE and West Nile virus. Contact your veterinarian for information regarding vaccinations.
