The federal government announced that iceberg lettuce at Taco Bell was to blame for the outbreak. But it still hasn’t answered some crucial questions.

Michigan, which is where much of the outbreak is centered, has reported over 4,300 cases of cyclosporiasis, which can cause diarrhea and a low grade fever.

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