OTTAWA, Ont. – Public health officials in Canada identified cooked diced chicken as the likely source of Listeria monocytogenes outbreak involving three provinces.

As of Aug. 18, there have been seven confirmed cases of Listeria in British Columbia (1), Manitoba (1) and Ontario (5). The case patients became sick between November 2017 and June 2019. Six individuals were hospitalized.

“The collaborative outbreak investigation was initiated because of an increase of Listeria illnesses that were reported in June 2019,” Public Health Agency of Canada said in a statement. “Through the use of a laboratory method called whole genome sequencing, two Listeria illnesses from November 2017 were identified to have the same genetic strain as the illnesses that occurred between April and June 2019.

“It is possible that more recent illnesses may be reported in the outbreak because of the delay between when a person becomes ill and when the illness is reported to public health officials,” the agency added. “This period is called the case reporting delay. In national Listeria monocytogenes outbreak investigations, the case reporting delay is usually between four and six weeks.”

In response to the investigation findings, Rosemount Sales and Marketing recalled its Rosemount brand of cooked diced chicken meat. The affected items include:

Rosemount Cooked diced chicken meat 13 mm – ½” (#16305); 4.54 kg; UPC 2 06 20263 12454 7; PACKDATE: 01/21/19.

The Canadian Food Inspection Agency is continuing its investigation into the matter and may result in recalls of additional products. The affected products were distributed in British Columbia, Alberta, Saskatchewan, Manitoba, Ontario, Quebec and Nova Scotia in addition to other provinces and territories.

Symptoms of Listeria infection can include fever, nausea, cramps, diarrhea, vomiting, headache, constipation and muscle aches. In severe cases, Listeria can spread to the brain, spinal cord and nerves. Symptoms of severe listeriosis include stiff neck, confusion, headache and loss of balance.

Listeriosis can be treated with antibiotics. But early diagnosis is key for individuals at high risk, such as pregnant women, older adults and people with weakened immune systems. Listeriosis in pregnancy can result in serious complications that include stillbirth, early delivery or infection in the newborn baby.

Foods susceptible to contamination with Listeria include raw or undercooked meat, poultry and fish, ready-to-eat meats such as hot dogs, pates and deli meats and unpasteurized raw milk cheeses and other food made from unpasteurized milk as well as pasteurized soft cheeses or mold-ripened cheese such as Brie and Camembert.