CHICAGO, Ill. (WTVO) — The Illinois Department of Public Health issued a warning Wednesday of a salmonella infection outbreak linked to ground beef.

According to the IDPH, 26 cases have been confirmed in Chicago, Cook County, Kane County, Lake County, McHenry County, and Will County.

Authorities say the illnesses began around April 25th.

The source of the ground beef has not yet been identified. Public health officials say ground beef should always be cooked to an internal temperature of 160° F.

Symptoms of illness caused by Salmonella most commonly include diarrhea (that can be bloody), fever, and stomach cramps. Some people may also have nausea, vomiting, or a headache. If these symptoms are experienced six to 72 hours after eating potentially contaminated beef, people should contact a health care provider and let them know they have recently eaten beef. The symptoms can last for four to seven days.

Salmonella can be found in a variety of foods, including beef, chicken, and pork. For this reason, it is important to follow proper hygiene for hands and utensils and to cook foods to the proper temperature. Always follow these four food safety steps to help prevent getting sick from Salmonella:

  • Clean: Wash your hands, utensils, and surfaces often.
  • Separate: Keep food that won’t be cooked separate from raw meat and poultry.
  • Cook: Use a food thermometer to make sure you have cooked your food to a temperature high enough to kill germs. For ground beef, it should have a minimum internal temperature of 160°F.
  • Chill: Refrigerate perishable food (food that goes bad) within 2 hours, or within 1 hour if food is exposed to temperatures above 90°F, like a hot car or a picnic. Thaw food in the refrigerator, not on the counter.