An outbreak of salmonella infections in the Chicago area has been linked to ground beef, the Illinois Department of Public Health said Wednesday.

Health officials have identified 26 confirmed cases in Cook, DuPage, Kane, Lake, McHenry and Will counties, the department said. Those people fell ill between April 25 and May 18.

A source of the tainted meat has not yet been identified, but health officials urged residents to follow safe food handling steps when preparing and eating ground beef, which should be cooked to an internal temperature of 160 degrees Fahrenheit and checked with a food thermometer.

126 ILLNESSES LINKED TO TASTE OF CHICAGO FOOD BOOTH

The Illinois Department of Public Health has linked salmonella infections in the Chicago area to ground beef. (Fox News)

A small number of salmonella cases in other states also are under investigation by the federal Centers for Disease Control and Prevention and state health departments, the Illinois agency said.

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Symptoms of salmonella infections most commonly include diarrhea, fever and stomach cramps. Some people may also experience nausea, vomiting or a headache. Symptoms can last for four to seven days.