New Brunswick (7), Nova Scotia (10) and Ontario (13).
According to the Canadian Food Inspection Agency, illness onsets began in late December and carried into early January.
Public health investigators have traced the likely cause of the outbreak back to California-grown lettuce distributed by Houston-based FreshPoint, Inc., and sold in Canada primarily to KFC and Taco Bell. Contaminated lettuce may have also been sold to Burger King, Pizza Hut and other retail locations as part of a salad mix. The lettuce was grown in California by a yet unnamed grower.