A source hasn't been determined in an outbreak of E. coli illness in Washtenaw County that was announced last week, but officials say it may be linked to cases reported in Ohio.

At least seven cases of the toxin-producing E. coli non-0157 strain have been confirmed to be related inside Washtenaw County, and another 14 are awaiting laboratory results.

The Columbus Public Health Department in Ohio is reporting five confirmed cases of E. coli non-0157, with several more pending confirmation, according to Washtenaw County's health department.

The source of the outbreak is believed to come from at least one Ann Arbor eatery, but which one has not been confirmed, said county health department spokeswoman Susan Cerniglia. Last week, officials said most of those sickened were young adults, and most live in Ann Arbor.

A common suspect for E. coli is leafy greens, although it has not been determined to be the suspect in this particular outbreak, Cerniglia said.

County officials are working with the state to investigate whether the food source of the exposure may have been from food supplied by a common food distributor that delivers food to several different restaurants, she said.

It is believed exposure to the bacteria occurred between April 7 and April 15. Those who eat contaminated foods typically experience symptoms about three to four days after eating the foods.

Symptoms include abdominal cramping followed by diarrhea that progressively worsens and is often bloody. Typically, there is no fever.

E. coli can be spread from cattle to people through eating raw or undercooked beef (especially ground beef). It can also be spread by consuming contaminated water or foods such as melons, lettuce, spinach, apple cider, alfalfa sprouts, or unpasteurized milk, according to a fact sheet from the county.

Infected individuals may spread the illness to others by not washing their hands well after a bowel movement. An adult infected with E. coli is contagious for a week. However, children may be contagious for up to three weeks.

Anyone who develops symptoms should seek medical attention and should report suspected E. coli illness to Washtenaw County Public Health at 734-544-6700.

Tina Reed covers health and the environment for AnnArbor.com. You can reach her at tinareed@annarbor.com, call her at 734-623-2535 or find her on Twitter @TreedinAA.