Michigan confirms two human Eastern Equine Encephalitis cases


LANSING, Mich. — The Michigan Department of Community Health confirmed two human cases of Eastern Equine Encephalitis (EEE) in Kalamazoo County Aug. 20.

Cases reported

A 61-year-old man is home recovering from the illness while a 41-year-old man is in intensive care in a Kalamazoo County hospital.

Both human cases have a history of local exposure to mosquitoes.

These are the first human cases reported in Michigan since 2002. No further details about the two cases are being released.

The health department and the Michigan Department of Agriculture are continuing to receive reports of cases of EEE in horses in southwest Michigan, including Barry, Calhoun, Cass, Kalamazoo, and St. Joseph counties.

What is EEE?

EEE is one of the most dangerous mosquito-borne diseases in the U.S., killing one third of those hospitalized with the infection, and often leaving survivors with lasting brain damage.

In addition to the human cases, 18 horses have tested positive for the virus, and the ag department has received more than 50 additional reports of deaths in horses. The southwestern region of the state has experienced outbreaks of this mosquito-borne disease in the past with the most recent outbreaks occurring in the early 1980s and mid-1990s.

Mosquito-borne illness will continue to be a risk in Michigan until late fall when nighttime temperatures fall below freezing.


Preventive steps need to be taken including wearing mosquito repellent and long pants and long sleeves when weather permits. Mosquitoes are most active at dusk and dawn.

Communities and land owners in high risk areas may consider the targeted application of insecticides (adulticides) to reduce the number of biting mosquitoes.

The Michigan Mosquito Control Association maintains a list of licensed mosquito control applicators on their Web site at www.mimosq.org.

Human symptoms

A virus of birds that is spread by mosquitoes, EEE is a rare illness in humans. Only a few human cases are reported each year in the U.S.

People who become ill with EEE may experience fever, headache, chills and nausea. In some cases, symptoms may progress to inflammation of the brain, signaled by disorientation, seizures and coma.

Physicians treating patients with these symptoms should consider testing for EEE and other mosquito-borne viruses and should report suspect cases to their local health department.

EEE is spread by mosquitoes and causes inflammation of the horses’ brains and leads to death in up to 90 percent of the cases. People cannot get the disease from horses, only from mosquitoes. There is a vaccination available to aid in prevention of the disease in horses.

Report it

“We want to encourage reporting of any signs, symptoms or deaths that appear to be related to this illness, even if the owner can’t afford the confirmatory tests,” State Veterinarian Steven Halstead said. Report suspect horse cases to MDA at: 517-373-1077 and after hours: 800-292-3939.

“Reports of illness in horses usually precede illness in people by days to weeks, so these reports serve as an early warning for the human population,” Halstead said.

Equine symptoms

Clinical signs in horses include: depression, fever, weakness, sweating, dehydration, seizures, abnormal facial expressions, not feeding, head down, stumbling, blindness and circling. Often, the horse is down and unable to get up.

“The majority of the 2010 affected Michigan horses were not currently vaccinated against EEE,” Halstead said. “It is not too late to vaccinate horses against this deadly virus.”

EEE is a reportable disease that also affects poultry such as chickens and emus.

Veterinarians are required by law to report cases of EEE. Livestock owners are also encouraged to report cases.

For updates on equine and human cases of EEE and other mosquito-borne diseases in Michigan, visit the Emerging Diseases Web site at www.michigan.gov/emergingdiseases.


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