Cyclosporiasis cases are on the rise in Illinois, with several new incidents, according to the Illinois Department of Public Health on Tuesday. The outbreak known for causing “explosive” diarrhea, has made up as many as 50 reported cases in Chicago. “At this time, no single source or cause of Chicago cases has been identified, and there is still no evidence of a large outbreak accounting for all or most of these Chicago cases,” the Chicago Department of Public Health said in a statement. Public health officials are investigating what the CDC said are “several clusters of cases in more than one state.” The investigation centered on four Midwestern states in particular: Michigan, Ohio, West Virginia and Kentucky. Cyclosporiasis is an infection caused by a parasite often linked to contaminated food and water. While lettuces are being investigated as a potential source, and have been the source for previous cyclosporiasis outbreaks, officials urged anyone eating or preparing lettuce or salad greens in areas where cases have been reported to take added precautions. Food items linked to cyclosporiasis are bagged salad mixes and kits, cilantro, fresh basil, raspberries, snow peas, and green onions.