The Canadian Diabetes Association is warning parents that it has served meat potentially tainted with listeria bacteria at a summer camp in Ontario.

After reviewing its supply of deli meats served at Camp Huronda, the association is telling parents to keep an eye open for symptoms of listeriosis in children who attended the camp.

Symptoms of the illness can appear up to 90 days after consuming food tainted with the bacteria.

An Ontario YMCA camp also alerted parents that it may have served potentially tainted meat during the summer.

Meanwhile, the death toll from the listeria outbreak has reached 13. Listeria has been deemed to have played a role in the death of an Ontario resident, previously considered a suspected case.