The FDA is investigating a cyclospora outbreak linked to McDonald's salads. ( File Photo )

The Food and Drug Administration is working to determine which ingredient in McDonald’s salads is the vehicle for a multistate cyclospora outbreak.

Sixty-one illnesses have been confirmed in Iowa, Illinois, Minnesota, Missouri, Nebraska, South Dakota and Wisconsin, according to a post on the FDA website. Two people have been hospitalized. No deaths have been reported. The ill people said they ate salads at McDonald’s before they became sick.

The FDA is working with the company to identify the common ingredients in the salads eaten by ill people and to trace back the ingredients. Investigators are also reviewing distribution and supplier information.

McDonald’s announced July 13 that it would stop selling salads at about 3,000 locations until it could switch suppliers.

The chain elected to make that adjustment at one or more restaurants in each of the following states: Illinois, Iowa, Indiana, Wisconsin, Michigan, Ohio, Minnesota, Nebraska, South Dakota, Montana, North Dakota, Kentucky, West Virginia and Missouri.

The statement by McDonald’s followed news releases by the Illinois and Iowa health departments that they had confirmed numerous cases of cyclospora in people who said they had eaten salads at the fast-food chain before becoming sick.

Illinois reported about 90 recent cases and said about 25% of the ill people reported eating at McDonald’s before they fell ill. Iowa reported 15 cases in which ill people said they had salads at McDonald’s and later got sick.

The Illinois Department of Public Health said people became ill starting in mid-May, while the Iowa Department of Public Health said ill people reported eating McDonald’s salads in late June and early July before getting sick.

The FDA does not currently have evidence to suggest this outbreak is related to an earlier cyclospora outbreak linked to Del Monte vegetable trays, per its update.