The disease is called Eastern Equine Encephalitis, and it's only the second time in U.S. history the disease has been found in deer.
There is a risk it can be transmitted to humans.
Steve Schmitt, a wildlife veterinarian with the Michigan Department of Natural Resources, said five deer infected with EEE have been found in Michigan; four in Kent County and one in Montcalm County.
The disease is found in birds. It was transmitted to the deer from mosquitoes, which makes it similar to the West Nile virus.
Schmitt said this disease is much rarer in humans than West Nile. The last human cases in Michigan of EEE were reported in 2002.
With the hunting season underway, health officials are warning hunters to protect themselves against mosquitoes. They're also asking hunters to take extra precautions when dressing a deer.
If you see a deer that appears to be sick, contact the Michigan DNR at 1-800-292-7800.