Michigan is home to a large number of mammals in the family of Squirrels. You may be familiar with the Eastern Red Fox Squirrel, the Easter Gray Fox squirrel, The Black vairation or phase of the Eastern Gray Fox Squirrel, and the Eastern chipmunk, but we also have nocturnal Southern flying squirrels, and the thirteen-lined ground squirrel in michigan. Below are pictures. Maybe you have seen all of these yourself!
Squirrels are typically not important vectors of disease - I don't think there's any documented cases of rabies transmission from squirrels, but that is not to say that it can not happen. Squirrels can carry rabies, they just work very hard to avoid people... but if they do have it and you corner one or try to touch it, it may bite you ad transmit the disease. Like all animals, squirrels can carry parasites, they leave behind excrement, and they can leave both in your attic. Squirrel droppings, like pretty much any wildlife dropping, are associated with Leptospirosis and Salmonella.
The biggest issue with squirrels and humans is when a squrrel makes your home into his home by getting into the attic. Like any of the varmints, squirrels need to chew constantly to keep their teeth from growing too much. Electrical wires, drywall, wood, insulation, and roofing material are all good candidates for keeping tooth growth at bay in the city squirrel's routine. STUDIES SHOW THAT UP TO 1/3 OF ALL HOUSE FIRES IN THE UNITED STATES CAN BE ATTRIBUTED TO ANIMALS THAT CHEW THROUGH ELECTRICAL WIRES. This includes squirrels, mice, and rats as well. DO NOT TAKE A SQUIRREL IN YOUR ATTIC LIGHTLY FOR THIS VERY REASON.
Squirrels can attack people if provoked. If you are bitten or scratched by a squirrel, please make sure you tell the nuisance control operator immeidately, as other precautions must be made on behalf of the state. Furthermore, seek immediate medical attention for the person who had contact with the animal.
Never touch a wild animal of ANY TYPE. You may jeapordize your health, the health and safety of the animal or its offspring, the demeanor of the animal, or the success that the animal will have on its own and without human intervention.
Squirrels are a very shy animal because they are pretty low on the food chain. In urban areas, squirrels generally make the most of predator fears of people and are quite prominent in most every backyard tree in the city and suburbs, where coyote, fox, and predatory birds tend to shy away.