The U.S. Centers for Disease Control and Prevention (CDC) is warning people not to eat shredded iceberg lettuce served at Taco Bell locations in Indiana, Kentucky, Michigan, Ohio and West Virginia.

Nearly 7,000 cases nationwide are confirmed or under investigation, according to the CDC. Michigan has accounted for the bulk of cases so far.

Shredded iceberg lettuce supplied by Taylor Farms and sold at some Taco Bell restaurants has been linked to a multistate outbreak of cyclosporiasis, a source familiar with the…