What Is Listeria And Why Does It Keep Triggering Massive Food Recalls?


On Tuesday, Trader Joe’s announced a recall of frozen vegetables that today expanded to another product, a prepackaged salad. TJ’s isn’t the only grocer with listeria recalls, either; Kroger has issued a recall on sunflower products. This comes on the heels of Starbucks recalling breakfast sandwiches and butter for the same reason. Naturally, Chipotle had this problem, too, because if it’s a contaminated food issue, Chipotle likes to have its hat in the ring.

So what is listeria? Why is it dangerous? And how does it keep getting into our food supply?

What Is Listeria?

“Listeria,” in this case, is short for Listeria monocytogenes, a relatively common foodborne pathogen. When you eat contaminated food, L. monocytogenes enters your bloodstream through the gastrointestinal tract and tries to set up shop. The good news is that, as a rule, it fails. In raw numbers, on average there are only 1,600 cases of serious listeria infection a year, according to the CDC.

But when you are infected, it’s dangerous. Listeriosis has a fatality rate of between 20 percent and 30 percent in high risk individuals.

It infects the central nervous systems of people with compromised immune systems, and can cause gastroenteritis in healthy people. Listeria is more dangerous than E. coli and even botulism. An outbreak caused by contaminated cantaloupe from Jensen Farms in Colorado killed 30 people.

Worse yet, listeria is absurdly hard to kill. It’s anaerobic, so you can cut off its oxygen supply and it won’t even notice. Put it in a freezer and it will continue to grow. Listeriosis can be passed from mother to fetus, which is why pregnant women aren’t supposed eat soft cheeses, as listeria easily grows on them. Antibiotics generally work, but only if the case is diagnosed in time.


This is why food recalls for listeria are so common. While the vast majority of us will be perfectly fine, it’s so dangerous when an outbreak does strike that recalling tons of food and destroying it is a far more palatable option for everyone involved. But how does this bug even get in our food?

A Common Bug

Listeriosis is uncommon in humans, but much more common in animals. That’s especially true of the animals we eat: Chickens, cows, sheep, and goats are all much more prone to listeriosis infection than humans. Because the bacteria is so hardy, it can live in soil for years, and all it takes is some poorly made silage or even just one of these animals eating dirt, and listeria will wind up in its tissues, in its milk, and in its manure.

Once it’s in an animal’s system, it can spread shockingly easily. For the cantaloupe outbreak, the FDA evaluated the entire facility, and theorized listeria could have gotten on the cantaloupe from used farm equipment, poorly sanitized equipment, or even just failing to install proper drainage.

Another issue is how far food now travels. The current listeria recalls, for example, are largely to do with sunflower seeds from one plant owned by food processor SunOpta. But just those seeds alone are on shelves under two different brand names, and on shelves across the country to be used in prepackaged products, like the salads Trader Joe’s is recalling. It’s not clear there’s even listeria on them, but if there is, this might be a far-ranging recall.

How To Stop It?

The main way to stop listeria, or any bacteria, is through basic food-safety practices. Wash any produce you’re going to use, even if you plan to cook it. You should cook any meats you plan on consuming, and if you’re concerned, avoid soft cheeses and raw milk, just to be safe.

And remember, listeriosis, while dangerous, is rare. It’s likely you’ve gotten the bacteria in your system and haven’t even noticed. So don’t let a fear of a bug dictate your food choices; just make sure you’re following food-safety rules, and you’ll be doing everything possible to prevent it with ease.