At least 20 Kentuckians have been sickened or a strain of E. coli bacteria, but the source of the outbreak hasn't been identified, the Kentucky Department for Public Health announced Friday.

Public health investigators suspect that some sort of food distribution is likely to blame for the sometimes life-threatening bacteria.

The cases involve both children and adults, many of whom reside in central Kentucky, the state said. No deaths linked to the outbreak have been reported but six people have been hospitalized.

State officials said health care providers across Kentucky have been notified of the outbreak and are advised to be alert for patients experiencing serious bouts of diarrhea, which could be associated with E. coli. The strain of E. coli involved (O103) produces a type of toxin (Shiga toxin) that can be dangerous for those infected.

"Exposure to E. coli bacteria can be debilitating and potentially life-threatening, especially for small children and individuals with weakened immune systems," state health commissioner Dr. Jeff Howard said. "We encourage all Kentuckians to be aware of the signs and symptoms of E. coli illness and to seek care if they are ill."

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Symptoms of E. coli O103 illness typically include stomach cramps and diarrhea, including bloody diarrhea, state officials said. People often become ill two to five days after eating contaminated food.

Those most at risk of developing serious complications from E. coli infection include the very young, the elderly and people with weakened immune systems, state officials said.

Mike Trautmann: 502-582-7081; mtrautmann@gannett.com; Twitter: @trautguy. Support strong local journalism by subscribing today: courier-journal.com/subscribe.

How to be safe from E. coli

The state offers these tips to help prevent E. coli infections:

Wash your hands frequently for at least 20 seconds with soap and warm water, especially before eating, after going to the bathroom, handling raw meat and eggs and after handling or petting animals.

Thoroughly wash produce before eating.

Thoroughly cook meat.

Clean and sanitize the areas where you prepare food.

Don't swallow lake or pool water.

Drink only pasteurized milk.

Frequently clean and sanitize restrooms, including doorknobs and faucets.

Report diarrhea to your doctor.

If you believe you have experienced symptoms of illness that could be associated with this E. coli outbreak, consult your health care provider or local health department.