ATLANTA (Michigan News Source) – The Centers for Disease Control and Prevention (CDC) is investigating an E. coli outbreak possibly linked to Wendy’s restaurants, including ones in Michigan.

On Friday, the CDC reported that 37 people in Michigan, Ohio, Pennsylvania and Indiana had been infected. Ten people have been hospitalized.

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The CDC has not yet confirmed the outbreak’s source, but the agency said 22 of 26 sick people reported eating sandwiches at Wendy’s before getting sick.

As a precaution, the restaurant chain said it would stop serving romaine lettuce in the region.