CHICAGO (WLS) — Illinois health officials are warning about a salmonella outbreak in the state linked to ground beef.

So far there’s no word on a specific source for the outbreak, but health leaders are telling people to follow safe food handling guidelines and cook their ground beef to an internal temperature of 160 degrees Fahrenheit, and checked with a food thermometer.

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So far 26 confirmed cases of salmonella have been identified in Chicago as well as Cook, DuPage, Lake, McHenry, Kane and Will counties.

The health department said people were sickened between April 25 and May 18.

Officials are still working on identifying the source of the contaminated ground beef.