4 Must-Know Facts About Listeria

Learn more about listeria contamination in food—and what you can do to protect yourself.

Man putting mayonnaise on a sandwich on a park bench.

Updated on May 31, 2023.

In 2020, its presence in enoki mushrooms affected 36 people across 17 states, resulting in four deaths. In 2021, it appeared in packaged salads, leading to 26 hospitalizations and four deaths. And in 2022, it caused 40 hospitalizations and two deaths when it was linked to ice cream and deli meats and cheeses.

What did these incidents have in common? Listeria monocytogenes, a type of bacteria that can be found in soil and water and that may be present in raw foods such as uncooked meats. Since 2011, listeria-contaminated foods have caused at least 20 outbreaks of infection in the United States.

Here’s what you should know about listeria, and how to stay safe.

How does listeria get in my food?

Listeria bacteria typically lives in soil, water, and animal feces. If it makes its way to a food-processing facility—such as through contaminated vegetables or meat—it can spread to products via dirty equipment or unhygienic plant conditions. The Centers for Disease Control and Prevention (CDC) advises you to steer clear of items linked to outbreaks of foodborne illnesses. That means if you have products that have been flagged by health authorities as being part of listeria outbreaks, toss ‘em.

What are the symptoms of infection?

“In healthy adults, listeria will simply cause a limited bout of food poisoning with vomiting and diarrhea,” says emergency physician Darria Long Gillespie, MD. “In these cases, symptoms usually start about 24 hours after eating the food with listeria.”

For people at highest risk, such as babies, pregnant women, older adults, and those with weakened immune systems, symptoms are more severe and can start on average 35 days after eating the contaminated food. Complications for pregnant women can lead to miscarriage, premature labor, and stillbirth. In the worst cases, listeria may cause serious illness, such as meningitis, and even death.

How is listeria infection treated?

A blood or spinal fluid test will show if you have listeriosis, the disease caused by listeria bacteria. A case of food poisoning from listeria doesn’t usually require antibiotics and symptoms tend to subside after about two days. For more severe infections, antibiotics are needed. Currently, ampicillin is the primary drug for treating the foodborne illness.

How can I avoid listeria?

You can’t fully eliminate the risk, but these tips can help keep you and your family safe.

  • Steer clear of foods most commonly associated with listeria, such as raw meat, cold deli meats, unpasteurized milk, sprouts, and smoked seafood.
  • Wash fruits and veggies and thoroughly cook meats. Be sure to scrub hard produce—like melons—before you cut into them.
  • Keep your refrigerator at 40°F or lower and the freezer at 0°F or lower. Unlike other bugs, these bacteria can live and grow in colder temperatures.
Article sources open article sources

ME Temple and MC Nahata. “Treatment of listeriosis.” Annals of Pharmacotherapy. 2000 May;34(5):656-61.
Centers for Disease Control and Prevention. “Listeria (Listeriosis): Prevention.” June 17, 2019. Accessed April 23, 2021.
Centers for Disease Control and Prevention. “Listeria (Listeriosis): Multistate Outbreak of Listeriosis Linked to Blue Bell Creameries Products (Final Update).” July 13, 2015. Accessed April 23, 2021.
Centers for Disease Control and Prevention. “Listeria (Listeriosis): Questions and Answers.” December 12, 2016. Accessed April 23, 2021.
Centers for Disease Control and Prevention. “Listeria (Listeriosis): Diagnosis and Treatment.” December 12, 2016. Accessed April 23, 2021.
Centers for Disease Control and Prevention. “Listeria (Listeriosis): People at Risk.” December 12, 2016. Accessed April 23, 2021.
Centers for Disease Control and Prevention. “Listeria (Listeriosis): Multistate Outbreak of Listeriosis Linked to Soft Raw Milk Cheese Made by Vulto Creamery (Final Update).” May 3, 2017. Accessed September 14, 2021.
Centers for Disease Control and Prevention. “Listeria (Listeriosis): Outbreak of Listeria Infections Linked to Enoki Mushrooms.” June 9, 2020. September 14, 2021.
Centers for Disease Control and Prevention. “Listeria (Listeriosis): Outbreaks.” Last Reviewed: February 15, 2023

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