On July 12, 2018 the Iowa Department of Public Health and the Illinois Department of Public Health reported an increase in cases of cyclosporiasis among people who ate salads sold at McDonald's fast food chain restaurants. The CDC also received reports of sick people from 15 states. Five hundred and eleven laboratory confirmed cases of Cyclospora infections were reported by people who consumed salads from McDonalds. Cases reported by 16 states. Illnesses started on or after May 20, 2018. Twenty-four people were hospitalized. There were no deaths.

On July 26, 2018 the FDA completed analysis of an unused package of romaine and carrot mix distributed to McDonald's by the Fresh Express processor in Streamwood, Illinois. Fresh Express reported that the carrots in the mix went to McDonald's restaurant locations only. The romaine lettuce was the only ingredient in the mix distributed to other locations. Romaine lettuce from the same lot that was positive for Cyclospora was distributed in pre-made salads and wraps distributed by Caito Foods LLC of Indianapolis, Indiana. On July 30 the USDA issued a public health alert about pre-made salads and wraps.