LANSING, Mich. – Public health officials in Michigan are investigating a small cluster of E. coli O157 illnesses in five counties.

Officials said five confirmed E. coli O157 illnesses have been reported in adults ages 20 to 41 years old with symptom onset dates from April 22 to May 1. No deaths have been reported, but three people have been hospitalized. The cases were reported from Kent, Livingston, Oakland, Ottawa and Washtenaw counties.

Laboratory results suggest the illnesses are linked to a common source, according to the Michigan Department of Community Health (MDCH). Laboratory results suggest the illnesses are linked to undercooked ground beef. MDCH said information collected from affected persons indicates they ate undercooked ground beef at several different restaurants.

E. coli O157 illnesses can be very serious or life-threatening, especially for young children, older adults, and people who are immunocompromised,” Dr. Matthew Davis, Chief Medical Executive at the MDCH said in a statement. “Whether you cook at home or order in a restaurant, ground meats, including ground beef, should always be cooked thoroughly to the proper temperature."

Investigators with the Michigan Department of Agricultural and Rural Development are working with the US Department of Agriculture to find the source of the ground beef and determine how widely the product was distributed.