U.S. authorities say 163 people have now been affected across 10 states by the multistate cyclospora outbreak linked to McDonald’s salads. 

The Centers for Disease Control (CDC) on July 13 announced it was investigating an outbreak of the parasitic infections, initially reporting a total of 61 confirmed cases in people who consumed salads from McDonald’s restaurants in seven states.

The CDC says there is no evidence to suggest that this cluster of illnesses is related to the ongoing cyclospora outbreak linked to Del Monte fresh produce vegetable trays.

The organization is advising people who have eaten a salad from a McDonald’s restaurant in Iowa, Illinois, Kentucky, Minnesota, Missouri, Nebraska, Ohio, South Dakota, or Wisconsin since mid-May and have become sick to see a healthcare provider.

Epidemiologic evidence indicates that salads purchased from McDonald’s restaurants are one likely source of these infections, it said.

The investigation is ongoing and FDA is working to determine the source of the ingredients used in the salads served at McDonald’s. The investigation has not identified a single, common ingredient in the salads linked to illness.

State and local health departments are interviewing ill people to find out what foods they ate in the two weeks before they got sick. Many ill people reported eating salads from McDonald’s restaurants located in the Midwest.