ST. LOUIS (KTRS) St. Louis County health officials say more than 20 cases of the illness known as cyclosporiasis have been confirmed since the end of May, of which 13 people reported having eaten premade salads. Health officials say most cases have been reported in West St. Louis County in the Ballwin-Chesterfield-Fenton areas and all cases have been found in adults aged 21 to 80 years old.

Cyclosporiasis is an intestinal illness that is usually contracted when people eat food or water contaminated with the parasite. Almost 100 cases have been reported in Illinois andin other states across the country. The outbreak prompted McDonald’s to pull its salads from its restaurants.