The latest Listeria contamination involves some plant-based beverages in Canada. However, from pre-packaged salads to six-layer bean dips to mushrooms, this isn’t the first time food or drink products have been recalled due to the bacteria.
Listeria monocytogenes, widely referred to as Listeria, can be found in soil, vegetation, sewage and water, as well as in the feces of both animals and humans, food safety organizations say.
People who eat foods contaminated with Listeria may carry the bacteria and not develop the listeriosis illness. But in other cases, it can be deadly.
“Once it gets in the system, it’s a bad bug to have,” said Dr. Michael Rieder, a professor in the department of pediatrics, medicine and pharmacology at Western University.
More than a week after the Canadian Food Inspection Agency (CFIA) recalled some oat, almond and coconut drinks from the Silk and Great Value brands, two people in Ontario have died from listeriosis.
In total, Ontario, Quebec and Nova Scotia have 12 confirmed cases related to this current outbreak, according to the Public Health Agency of Canada (PHAC).
In recent years, about 134 cases of invasive listeriosis have been reported annually in Canada, reports PHAC. Here’s what you need to know.
How common are Listeria contaminations?
In the last few months, several products have been recalled in Canada over possible Listeria contamination.
Most recently, enoki mushrooms, certain meat and vegetable products, as well as salad kits and bean dip, were recalled. None of these incidents led to confirmed cases or deaths in Canada, but products had to be tossed due to the risk.
Each province and territory tracks listeriosis cases, while PHAC issues public health notices when there’s an active outbreak that’s under investigation. PHAC also publicly tracks past outbreaks.
How does Listeria end up in our food and drinks?
“Each time you handle a food and process a food, [you] increase the chance of bacteria getting into it,” said Rieder.
It’s thought that “ultra-processed foods” are at a greater risk of having some type of bacteria in them compared to less processed ones, he said.
Keith Warriner, a food scientist at Guelph University in Ontario, says that outbreaks usually arise from a lapse in the plant’s sanitation practices.
“If you don’t do sanitation correctly, you don’t monitor it, it doesn’t matter how much you process it, it’s going to get contaminated,” he said.
How is it detected?
Though Rieder says well-established food and drink plants do take product safety “seriously,” monitoring for these contaminations isn’t always up to speed.
“The challenge we have is our detection tools are not perfect,” he said.
Currently, he says, small manufacturers test for bacteria by sending a sample out to a lab.
He says that not every province has a testing facility, so there can be a delay in getting the results back and, by that time, products have likely already been shipped and are sitting on shelves.
Warriner, in Guelph, adds that plants will typically test “maybe once a month, some once a week.”
Two people in Ontario have died after becoming sick with listeriosis linked to some Silk and Great Value plant-based milks. Catherine Donnelly, a professor emeritus at the University of Vermont who has studied listeria for decades, says consumers should pay attention to recall notices and look in their refrigerators if they think they may have consumed some of these products. Watch her full interview with Amy Smith.
“That sampling is to do with what we call verification, making sure the sanitation we’re doing is correct,” he said.
Rieder says there should be more in-facility testing so that plants get real-time results. A few years ago, he helped create a Listeria test kit, in the hopes of preventing affected products from hitting the shelves.
These kits have been approved by the U.S. Food and Drug Administration and by Health Canada for use in food plants and labs.
He says his team is currently working on a swab test that will help manufacturers test whether their environment is also bacteria-free.
What are the symptoms and when should you seek urgent care?
Listeria monocytogenes is a type of bacteria that can cause listeriosis, a rare but serious illness with symptoms that may start suddenly. But symptoms can also arise up to two months after the bacteria gets into your system.
“It’s sort of like a slow burn,” said Lori Burrows, a microbiologist at McMaster University in Hamilton, Ont.
“People may not connect the dots between what they ate and getting sick.”
Burrows suspects the delay in symptoms is partly why it can take so long to confirm the cause.
Symptoms can include:
- Vomiting.
- Nausea.
- Cramps.
- Severe headache.
- Constipation.
- Fever.
More severe illness may result in the brain infection meningitis and blood infection in newborns and older adults.
Women who are pregnant are also at high-risk, as the infection can lead to miscarriage and pregnancy loss.
“The mom may not feel sick, but it can be very dangerous for the fetus,” Burrows said.
Dr. Samir Gupta, a respirologist and associate professor of medicine in Toronto, says that if you know you’ve consumed a contaminated product and are feeling symptoms like fever, body aches and watery diarrhea, you should go see a medical provider, especially if you are part of an at-risk group.
For people who do have a weak immune system, doctors can prescribe antibiotics if they have diarrhea, according to Gupta.
He added that stronger antibiotics are given if the patient has a bloodstream infection. Studies suggest that delayed treatment can increase rates of complications and death.
How to protect yourself
Foods that are tainted with Listeria won’t look different, or have a distinct taste or smell.
When levels of the bacteria build up on equipment in food processing plants, outbreaks can occur. Listeria can be killed through cooking or pasteurization.
Researchers have shown that the bacteria can even survive in fridges and freezers.
Dr. Samir Gupta, a respirologist and associate professor of medicine, explains who is most at risk for listeriosis after the CFIA recalled several plant-based drinks over concerns the products may be contaminated with Listeria monocytogenes.
There’s a number of ways you can lower your risk of getting listeriosis, including washing your hands before and after handling food, cleaning fruits and vegetables and avoiding certain foods like raw, unpasteurized milk, soft cheeses or raw meats.
Here is where Canadians can keep track of product recalls and safety alerts.