If you’re like most grocery-store-going Americans—that is to say, pretty much everyone in the U.S.—you’ve probably heard about listeria outbreaks. Linked to about 1,600 cases every year, the foodborne illness is potentially deadly; it’s been blamed for as many as 260 deaths each year in the U.S. alone.
While it's been linked to numerous outbreaks over the years—Eggo waffles, caramel apples, frozen vegetables, and ready-made salads have all been subject to recent listeria-based recalls—the most serious outbreak in U.S. history occurred in the summer of 2011, when cantaloupe from a single Colorado farm sickened 147 people and killed 33.
Another example: the Blue Bell Creameries listeria outbreak of 2015, which seriously sickened 10 people in four states and ultimately claimed three lives in Kansas. The outbreak eventually forced the company to shut down all of its production plants and, in April of 2015, recall every one of its products on the market because of the risk of spreading particularly virulent strains of the disease.
Fortunately, as long as you stay up-to-date on recalls and take care to properly wash your fresh fruits and vegetables, you're pretty much safe from listeria and other foodborne illnesses. Here's what you need to know to eradicate it from your kitchen altogether:
What Is Listeria, Exactly?
Listeria specifically refers to Listeria monocytogenes, a bacteria that commonly shows up in dirt and water. It’s also unusually hardy, capable of growing in refrigerators and even surviving freezing temperatures—which is why frozen vegetables can still retain the bacteria. People are regularly exposed to trace amounts of listeria in everyday environments; when bacteria show up in food, however, it becomes problematic.
When someone contracts listeria bacteria and develops symptoms of an infection, the illness is called listeriosis. Listeriosis is a serious sickness, especially in pregnant women and people with weaker immune systems, since the bacteria almost always spreads beyond the gut, according to the Centers for Disease Control.
What Are the Symptoms of Listeriosis?
It ain’t fun: headache, fever, vomiting, muscle aches, stiff neck, confusion, loss of balance, and even convulsions can be linked to a listeriosis infection, according to the CDC.
If you experience those symptoms, get someone to take you to a doctor or emergency room fast. Complications of listeriosis include septicemia (an infection of the blood) and bacterial meningitis (infection of the cranial fluid), according to the Mayo Clinic.
In serious cases, listeriosis can be deadly. In pregnant women, listeriosis can even affect the viability of the birth.
What Foods Are Usually Linked to Listeria?
Because animals can carry listeria without symptoms, listeria is typically associated with uncooked meats and vegetables, unpasteurized milk and cheeses—queso fresco, Feta, Brie, and Camembert—and ready-to-eat deli meats (which can pick up the bacteria even after processing), according to the CDC. It’s also linked to refrigerated smoked seafood, refrigerated pâtés, and raw sprouts, according to FoodSafety.gov.
But listeria can potentially infect any number of foods, especially if it’s in contaminated refrigerators or production equipment, which is how it can infect other industrially produced types of foods, like waffles.
How Do You Prevent Listeria Contamination?
There are three basic steps you can take to keep this nasty bacterium out of your kitchen:
1. Clean your refrigerator, especially the drawers that hold your lunch meat, cheese, fruits, and veggies. Listeria bacteria can grow through spills and contact, and even refrigerated food is at risk. Think of it this way: When was the last time you scrubbed your fridge? If your answer’s “uuhhhh…” then it’s time to give it a deep clean.
2. Clean up your kitchen surfaces. Slicing open a watermelon? Prepping some raw chicken? Even though you probably prep it well before you serve it, you’d be surprised how easily bacteria can stick to countertops and cutting boards. Give your gear a good scrub after it makes contact with any risky foods or unwashed produce.
3. Be smart about listeria-risky foods. For people at risk, unpasteurized (aka “raw”) milk and cheeses are probably best avoided, and make sure you cook deli meats and hot dogs even if they’re pre-cooked, per the FDA.
It’s all pretty common sense. For more detail on food prep, check out the CDC’s recommendations.
What Are People Doing About Listeria?
Thanks to a combined effort from the CDC, FDA, USDA, and National Center for Biotechnology Information, as well as other groups, listeria’s entire genome is being sequenced so researchers can better combat the different strains of the bacteria. "Whole genome sequencing alone cannot solve outbreaks, but it has dramatically improved our ability to track Listeria and other germs," the CDC says.
In the meantime, be smart about keeping your kitchen clean, and you should have nothing to worry about.