Lansing, Mich. (WLNS) — Michigan officials are warning people who own horses to take precautionary measures this coming month amid rising case numbers of Eastern Equine Encephalitis disease, a deadly mosquito-borne illness that can infect both humans and animals.
The Michigan Department of Agriculture and Rural Development found cases of EEE in 2020 are already outpacing those from 2019.
As of September 13, EEE has been confirmed in 29 horses across 11 Michigan counties, which is twice the amount of animal cases at this same time last year, the department reported.
“We cannot state this strongly enough: horse owners and the general public need to take responsible, proactive steps to protect themselves and their animals from mosquito-borne diseases immediately,” said State Veterinarian Nora Wineland, DVM. “We don’t know if the dramatic increase in EEE equid cases is due to a lapse in vaccinations or a higher prevalence of EEE in Michigan’s mosquito population, but it doesn’t matter. If we ignore what’s happening, we run the risk of losing lives.”
So far this year, no humans have contracted the disease, but the Michigan Emerging Diseases Issues page states EEE is one of the most dangerous mosquito-borne diseases in the U.S. with a 33% fatality rate.
The first animal EEE case was confirmed in a 2-year-old filly in Clare County in August.
What is Eastern Equine Encephalitis?
EEE is a rare, mosquito-borne disease that ends up killing 33% of people who develop symptoms, but that percentage is much higher in horses at 90%. There is a vaccine for horses, but not for people.
What are the symptoms of Eastern Equine Encephalitis?
Most people who become infected with EEE do not develop any symptoms.
Only 4-5% of people will 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.
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.
And in one percent of people who are infected with EEE, encephalitis or meningitis can develop, which includes inflammation of the brain or surrounding tissues.
Those symptoms of neurologic illness include: high fever, headache, irritability, restlessness, drowsiness, anorexia, vomiting, diarrhea, bluish discoloration of the skin, convulsions, and coma. It is estimated that 30 percent of people who develop a neurologic infection due to EEE will die.
Who is more at risk for Eastern Equine Encephalitis?
If you frequently do outdoor work and recreational activities in endemic areas, you are at increased risk of infection.
People who are older than 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.
People older than 60 years 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.
Which areas are more risky for EEE 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.
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
- MDHHS BOL Mosquito-Borne and Tick-Borne Disease Testing
- Laboratory Testing
- Case Reporting
- Specimen Collection and Submission
How is Eastern Equine Encephalitis treated?
There is neither a human vaccine against EEE infection nor a 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.
How can you prevent Eastern Equine Encephalitis?
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.
For more educational materials, data and statistics about Eastern Equine Encephalitis disease, visit Michigan.gov/EmergingDiseases