Shredded lettuce is one possible culprit, although it’s highly likely there are other sources of the foodborne illnesses making people sick across the U.S.

Centers for Disease Control and Prevention says they are scouring food supply chain for culprit, which may be lettuce

In Michigan — where more than 3,300 cases have been reported — officials say early information points to lettuce or salad greens as a possible culprit.