More than 100 people have been infected with a parasitic outbreak from consuming McDonald’s salads.

Both the Iowa and Illinois health departments are currently investigating the cause. Since May 90 people in Illinois and 15 people in Iowa, have come down with the cyclospora parasite after eating salads from McDonalds.

Cyclospora is a parasite that causes intestinal illness, resulting in diarrhea and troubling bowel movements. The Illinois Department of Public Health said illnesses have been reported in multiple counties in the state.

Those infected with cyclospora may experience a range of symptoms such as vomiting, loss of appetite, stomach cramping, fever, nausea, fatigue and more. The illness can last anywhere from a few days to a few months and come back, even after symptoms disappear.

In an email statement, McDonald’s said it was voluntarily recalling its salads at the impacted locations until another lettuce supplier can be found. “We are in the process of removing existing salad blend from identified restaurants and distribution centers — which includes approximately 3,000 of our U.S. restaurants primarily located in the Midwest,” it said.

McDonald’s is actively working with the U.S. Centers for Disease Control and Prevention and the Food and Drug Administration to locate the cause of the outbreak. Anyone who has eaten a salad from the fast food chain is encouraged to contact their health care provider.

Cyclospora is commonly found in contaminated food or water. This summer, Del Monte Fresh experienced an outbreak of the parasite in its vegetable food trays. It has been linked to more than 200 illnesses across four states in the country.