Mosquito-borne virus threat grows with new Michigan cases

Michigan health officials amped up their warning about a rare mosquito-borne virus Tuesday, after the state's Department of Health and Human Services confirmed four new cases of Eastern equine encephalitis disease (EEE). Two of the state's seven cases so far this year were fatal.

"Michigan is currently experiencing its worst Eastern equine encephalitis outbreak in more than a decade," Dr. Joneigh Khaldun, chief medical executive and chief deputy for health said in a statement.

"The ongoing cases reported in humans and animals and the severity of this disease illustrate the importance of taking precautions against mosquito bites."

There are typically about seven cases of EEE reported each year in the U.S., according to the U.S. Centers for Disease Control and Prevention, with those cases tending to be clustered along the Eastern Seaboard and in the Great Lakes regions.

In addition to Michigan, a handful of states, including North Carolina and Massachusetts have seen an uptick in cases, bringing this year’s total to 28.

Last year there were only six cases reported nationwide.

EEE is transmitted by mosquitoes, usually in swampy areas where mosquitoes breed, so people who spend time working or participating in outdoor activities are at higher risk for contracting EEE. The disease cannot be transmitted from person to person. Symptoms of EEE include chills, fever, fatigue, and joint and muscle pain, which tend to set in around four to 10 days after being bitten by an infected mosquito.

About 30% of people who develop the disease will die of the infection and among those who survive, many will experience neurological problems, ranging from seizures to intellectual impairment to personality disorders, according to the CDC.

To avoid being bitten, health officials recommend using mosquito repellent containing DEET and wearing long-sleeved shirts and pants while outdoors, as well as emptying standing water around the home to reduce mosquito breeding grounds.

Health officials don’t know exactly what’s causing the uptick, since unlike more prevalent mosquito-borne infections, like West Nile virus, there’s not much research on what causes mosquitoes to carry EEE in a given year, a Michigan health department spokesperson explained.

Editor's note: A previous version of this story stated that there were 73 cases of Eastern equine encephalitisin 2019. There have been 28 cases so far this year. The story additionally named New York, Florida and Georgia as states with EEE cases this year. While those states have recorded cases in previous years, this year they have not