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.

An outbreak of diarrhea caused by the parasite cyclospora has risen to more than 3,000 cases in Michigan and Ohio.

The foodborne gastrointestinal illness has shown up in 31 states, and federal health officials say 86 people have been hospitalized.