Listeria: What is it and should I be worried?

A comprehensive list to avoiding Listeria

In recent months, two national food distributors have issued nationwide recalls of products for fear they contain Listeria. Although no cases have been reported in Greater Louisville, several questions have been raised as to what it is and how to steer clear of it.

According to the Centers for Disease Control and Prevention (CDC), Listeria is a type of bacteria and among the most dangerous foodborne illnesses, particularly to people with compromised or weak immune systems.

Kris Bryant, M.D., infectious disease specialist with Norton Children’s Hospital and UofL Physicians, says symptoms will depend on a person’s present state of health.

Looking at the general population, if a healthy person has consumed food contaminated with Listeria, he or she may have no symptoms or may have fever, muscle aches, vomiting, diarrhea and abdominal pain.

 “Those who get the sickest with Listeria are pregnant women, their unborn or newborn babies, older adults and those with weak immune systems,” Dr. Bryant said. “For example, pregnant women can get a flu-like illness or may go into preterm labor and birth; and babies who are born to moms with Listeria may develop sepsis or meningitis.

 “Adults 65 years and older or those who are immune-compromised, such as those with cancer, who have had an organ transplant or have an ongoing illness, may develop a bloodstream infection or an infection of the brain,” Dr. Bryant said. “These types of infections can be fatal.”

Listeria differs from many other types of bacteria because it can grow even in cold temperatures. Listeria is killed by cooking or through the pasteurization process.

Some common sources of Listeria include:

  • Ready-to-eat deli meats and hot dogs
  • Refrigerated pâté or meat spreads
  • Unpasteurized (raw) milk and dairy products
  • Soft cheese made with unpasteurized milk (e.g., queso fresco, feta, brie, Camembert)
  • Refrigerated smoked seafood
  • Raw sprouts

The incubation period for Listeria can range from one day up to 70 days. Unlike the flu, Listeria usually isn’t spread from person to person but rather people are infected by eating tainted food products. The exception to this is pregnant or breastfeeding women, who can pass it to their unborn or newborn child.

Tips for staying safe from Listeria:

  • Do not drink raw (unpasteurized) milk, and do not eat foods that have unpasteurized milk in them.
  • Wash hands, knives, countertops and cutting boards after handling and preparing uncooked foods.
  • Rinse raw produce thoroughly under running tap water before eating.
  • Keep uncooked meats, poultry and seafood separate from vegetables, fruits, cooked foods and ready-to-eat foods.
  • Thoroughly cook raw meats, including poultry and seafood, to a safe internal temperature.
  • Consume perishable and ready-to-eat foods as soon as possible.
  • If you are in a high-risk group because of your health, heat hot dogs, cold cuts and deli meats before eating them.
  • Pregnant women and others at high risk should not eat soft cheeses such as feta, queso blanco, queso fresco, brie, Camembert, blue-veined or panela (queso panela) unless it is labeled as made with pasteurized milk.

For more tips on food safety, visit

Someone who has eaten a recalled food product but has no symptoms generally doesn’t need tests or treatment. People with questions, particular those at higher risk, should discuss their concerns and exposures with their doctor.


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