Public health officials are investigating an outbreak of intestinal illnesses in Illinois and Iowa that affected dozens of consumers who ate salads from McDonald's.

Illinois is reporting 90 cases since mid-May linked to the cyclospora parasite, with more than 20 of those cases involving consumers who ate salads at McDonald's restaurants. Iowa has recorded 15 cases since late June.

Cyclospora can cause stomach cramps, nausea and flu-like symptoms a week or more after the consumption of food or liquid contaminated with the parasite.

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"If you ate a salad from McDonald's since mid-May and developed diarrhea and fatigue, contact a health care provider about testing and treatment," Dr. Nirav Shah, director of the Illinois Department of Public Health, said in a statement on the agency's website.

While finding a link to salads sold at McDonald's in about a quarter of the Illinois cases, the state is also looking into other possible sources for the contamination, Shah added.

McDonald's is working with officials in the two states and has temporarily stopped selling salads at the restaurants identified as possible sites for the contamination, according to a company spokesperson, noting that McDonald's will also switching lettuce suppliers.

The fast-food company also said it is removing its existing salad blend from about 3,000 of its outlets, most of them in the Midwest.

The parasite cyclospora is also involved in the recall of Del Monte Fresh vegetable trays, blamed for sickening more than 200 people in Iowa, Indiana, Minnesota and Michigan.

As of Friday, the Centers for Disease Control and Prevention had confirmed 227 cases of cyclosporiasis, with seven people hospitalized. Two cases from Michigan reportedly involved vegetable trays purchased in Wisconsin, federal authorities said.