McDonald’s salads have been linked to 163 “laboratory-confirmed” cases of cyclosporiasis across 10 U.S. states, according to the Centers for Disease Control.

The foodborne illness has been reported in Ohio, Kentucky, Florida, Illinois, Iowa, Minnesota, Missouri, Nebraska, South Dakota, and Wisconsin, according to the CDC’s case count map, and the majority of the illnesses have been found in Illinois and Iowa. Three people have been hospitalized and there have been no reported deaths.

Cycolspora is a single-celled parasite that causes an intestinal illness called cyclosporiasis. It takes around a week after exposure for symptoms to appear, and while some people experience no symptoms, others may have “watery diarrhea, with frequent, sometimes explosive, bowel movements,” the CDC explains. Gas, nausea, stomach cramps, and loss of appetite are also associated with cyclosporiasis, and some who are infected experience flu-like symptoms. The symptoms can last from a few days to a month, and patients should be diagnosed and treated by a health care professional.

Cyclosporiasis is contracted by ingesting food or water that has been contaminated with feces. “Cyclospora needs time (typically, at least 1–2 weeks) after being passed in a bowel movement to become infectious for another person,” according to the CDC. “Therefore, it is unlikely that Cyclospora is passed directly from one person to another.”

On July 13, McDonald’s voluntarily stopped selling the salads at 3,000 locations across the Midwest—including Illinois, Indiana, Iowa, Kentucky, Michigan, Minnesota, Missouri, Montana, Nebraska, North Dakota, Ohio, South Dakota, West Virginia, and Wisconsin. And the fast-food chain is cooperating with investigations being done by the CDC, Food and Drug Administration, and local officials.

“The health and safety of our customers and the people who work in McDonald’s restaurants is always our top priority,” McDonald’s said in a statement. “The additional states identified by the FDA and CDC are among the same states where a week ago we proactively decided to remove our lettuce blend in impacted restaurants and replace it through a different supplier.”

The CDC recommends seeing a health care professional if you ate a salad at McDonald’s as far back as mid-May in the impacted states.

Another cyclosporiasis outbreak has been linked to Del Monte vegetable trays, but the FDA says there is no evidence that the two are related.