A McDonald's apple walnut salad.
Richard Lautens—Toronto Star via Getty Images
July 14, 2018 3:17 PM EDT

McDonald’s salads may be to blame for a parasitic illness outbreak that has sickened more than 100 people in Illinois and Iowa, according to public health officials.

Since mid-May, Illinois alone has seen more than 100 cases of cyclosporiasis, an intestinal illness caused by the parasite cyclospora, according to an announcement from the Illinois Department of Public Health. Iowa is experiencing a similar outbreak, according to a statement from the Iowa Department of Public Health.

McDonald’s salads may be the culprit in both states, according to the announcements. Twenty-nine people in Illinois and at least 15 people in Iowa reported eating salads from the fast-food chain before getting sick.

“Out of an abundance of caution, we decided to voluntarily stop selling salads at impacted restaurants until we can switch to another lettuce blend supplier,” McDonald’s said in a statement. “We are in the process of removing existing lettuce blend from identified restaurants and distribution centers – which includes approximately 3,000 of our U.S. restaurants primarily located in the Midwest.”

These restaurants span Illinois, Iowa, Indiana, Wisconsin, Michigan, Ohio, Minnesota, Nebraska, South Dakota, North Dakota, Montana, Kentucky, West Virginia and Missouri, according to the statement.

People become sick with cyclosporiasis after eating food or drinking water carrying the parasite, according to the Centers for Disease Control and Prevention. Symptoms include watery diarrhea, appetite loss, stomach pain, bloating, gas, nausea and fatigue.

Write to Jamie Ducharme at jamie.ducharme@time.com.

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