Frozen waffles from Whole Foods join recall list in Canada: What is listeria, and what are the symptoms?

This article is for informational purposes only and is not a substitute for professional medical advice, diagnosis or treatment. Contact a qualified medical professional before engaging in any physical activity, or making any changes to your diet, medication or lifestyle.

Another brand of waffle products sold in Canada is being recalled due to fears of listeria contamination, joining a growing list of brands part of a voluntary recall earlier this week. A food recall warning published Friday indicated frozen waffles from Whole Foods Market might be contaminated.

The latest recall from the Canadian Food Inspection Agency (CFIA) warned about two products from the 365 Whole Foods Market brand: The organic blueberry and homestyle waffles sold in British Columbia, and possibly other parts of Canada.

"There have been no reported illnesses associated with the consumption of these products," the recall warning noted. It added the CFIA is verifying these products are removed from the marketplace.

Last Friday, TreeHouse Foods announced it was voluntarily recalling hundreds of frozen waffle products under various brand names following "routine testing at the manufacturing facility" in Ontario. The products were sold throughout Canada and the United States, but no confirmed illnesses had been reported.

What frozen waffles were recalled?

A complete list of products included in the recall — including associated lot codes — can be found at the bottom of TreeHouse Foods' press release. Photos of the products associated with the recall are available online. On top of the Whole Foods Market products, the others include the brands:

• No Name

• Great Value

• Selection

• Compliments

• Breastfast Best

• Western Family

• Always Save

• Best Choice

• Bettergoods

• Clover Valley

• Essentials

• Food Lion

• Food Hold

• Giant Eagle

• Good & Gather

• Hannaford

• Harris Teeter

• H-E-B Higher Harvest

• Kodiak Cakes

• Pics by Price Chopper

• Publix, Schnucks

• SE Grocers

• Simple Truth

• Tops

What exactly is listeria and why is it dangerous if consumed? Here's what you need to know — and which symptoms of listeria to look out for.

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," Bogoch said 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 of a listeria infection?

The CFIA 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," Bogoch said.

Is listeria dangerous for everyone?

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, 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," the 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."

Is listeria contagious?

People become infected by listeria by consuming contaminated products. Listeria infections don't spread from person to person. However, it's possible for a pregnant person to pass a listeria infection to their unborn fetus.

How to prevent listeria 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," he said.

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, adding fruits and vegetables should also be washed thoroughly.

Let us know what you think by commenting below and tweeting @YahooStyleCA! Follow us on Twitter and Instagram.