The Illinois Department of Public Health is working with other health agencies to investigate a multi-state outbreak of E. coli.
Officials say of the 38 people infected, four are from Illinois. There have been no reported deaths.
According to a news release, flour produced at a General Mills facility in Kansas City, Missouri is a likely source of the outbreak.
It also says on May 31, the company recalled several sizes and varieties of Gold Medal Flour, Gold Medal Wondra Flour, and Signature Kitchens Flour due to possible E. coli contamination.
The four infected individuals in Illinois live in Chicago, suburban-Cook, Brown, and McHenry counties.