Listeria outbreak in U.S. that led to 2 deaths, 23 hospitalizations prompts Canadian recall

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The Canadian Food Inspection Agency (CFIA) has issued a recall of salad kits and six-layer dip after a deadly outbreak of listeria in the United States.

On Wednesday, the CFIA issued a recall notice for President's Choice and Taylor Farms Mexican-Style Street Corn Salad Kits, which were distributed nationally, as well as Rojo's brand Black Bean 6 Layer Dip, which was distributed to Ontario, Quebec, New Brunswick and Newfoundland and Labrador.

Both products were made with cheese Rizo-López Foods Inc., a company that has been identified as the source of a multi-state listeria outbreak which has resulted in 26 cases of listeria infections, 23 of which required hospitalization, and two deaths.

On Tuesday, the U.S. Food and Drug Administration (FDA) shared information about its "multi-year, multi-state" investigation into the outbreak, which includes cases dating back to 2014. States with reported infections include Arizona, California, Colorado, Florida, Georgia, Nevada, North Carolina, Oregon, Tennessee, Texas and Washington.

What exactly is listeria? Here's what you need to know.

What is listeria?

Dr. Isaac Bogoch, an infectious diseases specialist at the Toronto General Hospital, described listeria as a type of bacteria that can infect people when they consume contaminated food.

"It's usually associated with specific types of food," said Bogoch in a September 2023 interview. "It's just more common in some foods than others. But it's sadly not uncommon to hear about listeria outbreaks from time to time."

He said listeria can be found in:

• Cold cuts, deli meats and hot dogs

• Pasteurized or unpasteurized milk products

• Store-made salads

• Occasionally, in fruits and vegetables

"The interesting thing about listeria is that, normally when you put something in the refrigerator, it usually would suppress bacterial growth, but listeria actually grows very well in refrigerated environments," Bogoch explained.

What are the symptoms?

The Canadian Food Inspection Agency said food contaminated with listeria may not look or smell spoiled, but can still make people sick.

According to public health, symptoms of listeria can start as early as three days after eating contaminated food.

The symptoms can include the following:

• Fever

• Nausea

• Cramps

• Diarrhea

• Vomiting

• Headache

• Constipation

• Muscle aches

"Most people who get listeria are going to have diarrhea and gastrointestinal symptoms. It's going to go away on its own. They don't even require antibiotics. ... And a lot of people probably had listeria and did not even know it," said Bogoch.

Who is at risk?

Pregnant women, the elderly and people with weakened immune systems are particularly at risk for severe illness from listeria, according to Bogoch.

"Those individuals are at risk of what we call invasive listeriosis," said Bogoch. "And that means it can cause a bloodstream infection. ... it can be very serious."

According to the World Health Organization (WHO), invasive listeriosis is characterized by "severe symptoms and a high mortality rate (20 to 30 per cent)."

The symptoms include:

• Fever

• Myalgia (muscle pain)

• Septicemia (blood poisoning)

• Meningitis (inflammation of brain and spinal cord tissues)

"The incubation period is usually one to two weeks but can vary between a few days and up to 90 days," WHO explained.

The infection in pregnant women may also lead to premature delivery, infection of the newborn or even stillbirth.

However, Bogoch said listeria is generally not difficult to treat and people who do end up hospitalized will get antibiotic therapy.

"The key is prevention," he added, "to ensure that people are aware of what product is involved so they can avoid it ... and if people do have risk factors for a severe infection and they have symptoms of infection, to ensure that there is rapid access to care and they start treatment."

How to prevent infection?

Bogoch said food contaminated with listeria is beyond an individual's control and it has to do with how the food was processed before it reached the consumer. But, there are still ways to prevent infection.

"People can cook their meat. ... The bacteria would not survive if you cooked a hot dog," said Bogoch.

Health Canada said "foods that are contaminated with the listeria bacteria will look, smell and taste normal."

This is why people at high risk for severe illness should avoid eating deli meats unless they are dried and salted, or heated until steaming hot. Additionally, they should avoid pâté and meat spreads unless they are frozen, canned or shelf-stable.

To lower the risk of infection, Bogoch also recommended people avoid unpasteurized dairy products, which Health Canada said includes soft and semi-soft cheese such as brie, camembert and blue-veined cheese.

"People can still get listeria through pasteurized products ... but unpasteurized products carry a higher risk," Bogoch said.

Fruits and vegetables should also be washed thoroughly, the doctor concluded.

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