Two of those people were hospitalized but no deaths have been reported.
McDonald's has removed salad options from 3,000 locations after consumers report getting sick.
When ingested, it can cause a non-life-threatening intestinal illness called cyclosporiasis, according to the Centers for Disease Control and Prevention. The fast food chain has stopped selling salads at its 3,000 restaurants.
"Anyone who ate these salads since the middle of June and who developed diarrhea, especially watery diarrhea and fatigue, should see their health care provider and get tested for Cyclospora to ensure an accurate diagnosis and appropriate treatment".
IL reported 90 cases since mid-May while Iowa had 15 cases since late June.
"Out of an abundance of caution, we made a decision to voluntarily stop selling salads at impacted restaurants until we can switch to another lettuce blend supplier", McDonald's said in a statement released Friday. The Illinois Department of Public Health said it had recorded about 90 cases since mid-May, and the Iowa Department of Public Health said it had recorded 15 cases since late June. Common symptoms include loss of appetite, diarrhea, cramping and bloating.
McDonald's is cooperating with the health officials during the investigation. Vomiting, headache, fever, body aches and flu-like symptoms can also occur.
Cyclospora cayetanensis is a parasite that can contaminate food and water through feces.