Like most people, I’ve been infected with a “stomach bug” from time to time. You know the symptoms: vomiting, diarrhea, fever, chills and muscle aches. The culprit causing my discomfort was very likely listeria monocytogenes, a nasty bacterium that lives everywhere and can be transferred in many ways.
And if you watch tv, read the paper, or participate in social media of any kind, you’ve no doubt read or heard of people becoming extremely sick due to food tainted with “listeria” and that begs the question:
Can Listeria Be Washed Off of Food?
Thorough washing of food is a good first step but washing should be done in a certain way in order to give us the best chances of removing pesky, clingy listeria bacteria.
Read on for our washing instructions and you’ll also discover how listeria gets in our food supply in the first place, and other ways that will help protect you and your family from becoming listeria’s next victim.
How does produce get listeria?
Listeria lives in soil and water and can survive very low temperatures. How does it get there and how does it end up on our produce? Usually it arrives in infected animal waste, some of which is often mixed with water for spray-fertilizing crops.
That mental image alone motivates me to wash my produce! Bacteria hidden in meats and cheeses made from unpasteurized milk can also spread it by contact with raw veggies and fruit. Fruits grown close to the ground, like strawberries, are perfect listeria hotbeds.
Especially risky are hot dogs and cold cuts like bologna. I protect my veggies by making sure juices don’t leak into the produce drawer and I prevent contact with the meats and cheeses themselves.
How does listeria spread?
Listeria are opportunistic critters, taking every chance to move to a new home. We sometimes transfer listeria to our food with contaminated hands, counter surfaces and cutting boards. Dishcloths, cutting boards and towels or sponges can also spread it from a source like chicken or meat to foods we eat raw.
Hand washing and sterilized or disinfected surfaces and kitchen tools are critical to prevent cross-contamination. Always use separate cutting boards for raw meats and eggs, others for salads and other raw veggies.
Listeria can also spread in the refrigerator, even if the temperature is kept at the recommended 40°F or lower! Listeria can spread from contact with refrigerator walls and shelves, or by foods that touch each other.
The food industry is accountable for at least some of the listeria outbreaks in recent years. Production facilities and farms are especially culpable when they don’t clean equipment sufficiently, and some produce packers wash fruits and vegetables in contaminated water, making it harder for consumers to avoid the stomach bug.
Washing Food to Effectively Remove Listeria
Vinegar Soak – For foods that will be eaten raw, a soaking spray with a mixture of white vinegar and water that’s left on for 30 minutes goes a long way toward reducing the number of bacteria and loosening adhesion.
Even foods like avocados and fruits that will be peeled before eating need to be soaked then rinsed well before cutting or biting into them to avoid transferring the listeria to the inside.
Water Pressure – Most kitchen faucets have a standard flow rate of 2.2 gallons per minute which is good. This 2.2 was proven to be most effective for removing clinging listeria from food. Bad news for Californians who have imposed flow rate restrictions on faucets of 1.8 gallons per minute.
If you’re shopping for a new faucet, always choose at least 2.2 gallons per minute flow rate or at the very least, be sure to attach a higher pressure aerator for washing vegetables. Selecting models with a high pressure hose is worth the investment.
TIP: To Learn About Killing Listeria on HARD Surfaces read this article (link).
What are other ways listeria infection can be prevented?
While exposing listeria to heat eradicates it, none of us want cooked lettuce and celery in our salads! Rinsing continues to be an effective weapon against infection from raw foods. Fruits and veggies have natural nooks and crannies that are impossible to reach with plain water so use a vegetable brush when rinsing to get the most out of the process.
Check cheese labels, especially soft cheeses like Brie, Camembert, and queso, to be sure they’re made with pasteurized milk. Toss common culprits, especially deli meats and cheeses, cold cuts, hot dogs and smoked fish, within a week of purchasing and/or opening sealed packages.
You don’t have to wash your eggs (unless you’re buying straight from the farm). But do make sure to check the “best by” date and use or discard them before they expire. The CDC tells us that we should NOT wash meats, fish and chicken before cooking.
Can listeria be cooked out?
Yes, Listeria bacteria are killed by thorough cooking, and in the case of dairy products by pasteurization. The CDC even suggests steaming sandwich meats and cold cuts until they’re piping hot before eating them.
Vegetables and meats meant to be eaten hot need to be cooked completely, eaten promptly and stored in the refrigerator within 2 hours after preparing. A food thermometer is a great way to check for the appropriate cooking temperature, typically 165°F. So much for my passion for medium rare steak!
Listeria and Pets
Listeria is an equal opportunity bug and can easily be picked up by pets, who can then infect their owners. Senior pets and puppies or kittens are at especially high risk for death from a listeria infection. Any pet can be exposed to it through their food, even when feeding high quality, trusted brands.
Raw food diets are of special concern, but kibble and canned food can harbor the bacteria too. While I love to treat my pups with human leftovers and table scraps I ensure they’re cooked well and I never give them raw hot dogs, cold cuts or meat and soft cheeses.
Use care when cleaning the litter box or bird cage and cover hands with a hole-less plastic bag or glove before picking up your dog’s poop. And remember to wash your hands afterward! There’s no evidence that pets’ saliva can spread the bacteria, but this is still being studied.
Watch for pet food recalls on a regular basis and check with your veterinarian for other concerns. Listeria can usually be treated, but the vet bill for IV fluids and antibiotics can reach $1200 or more. Ouch!
Because untreated listeria infections (listeriosis) in vulnerable people can move to the brain and other parts of the central nervous system, causing often-fatal meningitis, it’s important to be vigilant to prevent its spread and get prompt treatment for a suspected listeria infection.
Most stomach bugs pass within a couple of days without being diagnosed but pregnant women and their fetuses, newborns, seniors and immune-compromised folks (think HIV, diabetes) are especially prone to serious secondary infections. A simple test for listeria can point the way toward effective treatment.
Washing raw produce is still the first step for consumers but you and I need to be aware of other ways to prevent this unpleasant infection.