GRAND RAPIDS, Mich. (WOOD) — An increase in Eastern Equine Encephalitis cases found in animals has led to aerial spraying over several counties in Michigan.

The spraying continued Monday night and Michiganders are being asked to use caution when outdoors.

The cooler temperatures have not done much to the threat of EEE and won’t until there is a deep freeze to kill off many of the mosquitoes, according to the Michigan Department of Health and Human Services.

“We are continuing to see animal cases of EEE rise, increasing the urgency for treatment to continue as we know the mosquitoes carrying this potentially deadly virus are still active in our state,” said Dr. Joneigh Khaldun, chief medical executive and chief deputy for health at MDHHS.

So far, 30 horses have the disease, along with two deer.

The counties impacted are scatted across the state with spraying happening in Kent, Barry, Montcalm, Newaygo, Oceana, Muskegon, Allegan, Calhoun, Jackson, Livingston and Oakland counties.

There has been one confirmed human case in Barry County.