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Listeria Monocytogenes, Listeriosis, and You

The Centers for Disease Control and Prevention’s June issue of Vital Signs focuses on the health risks associated with the foodborne pathogen Listeria monocytogenes.  Certain foods are more likely to pose of higher risk of contamination with Listeria monocytogenes, as outlined in a recently published risk assessment,  Listeria monocytogenes in Retail Delicatessens, by USDA’s, Food Safety and Inspection Service and the FDA’s Center for Food Safety and Applied Nutrition.

What is Listeriosis?

The infection caused by ingesting food contaminated with Listeria monocytogenes is called Listeriosis.  Listeriosis is relatively rare but can be fatal, especially in people at high risk for infection, such as older adults, pregnant women and infants, as well as people with compromised immune systems (cancer, diabetes, or HIV/AIDS patients, and transplant recipients).

Listeriosis usually causes fever and muscle aches, but symptoms can also include headache, stiff neck, confusion, loss of balance, and convulsions. In pregnant women, listeriosis can cause miscarriage, stillbirth, and serious illness or death in newborn babies. People who think they might have become sick with listeriosis should consult their doctor.

How Does Listeria get into our food?

Listeria is found in the environment – in soil, water, decaying vegetation, and the intestinal tract of animals.  If food is processed, packaged, or handled in unsanitary conditions, it can become contaminated with Listeria. This is of particular concern with ready-to-eat, refrigerated foods, such as luncheon meats, patés or meat spreads, because most of these are not reheated before eating – a step that would kill Listeria. In addition, unpasteurized milk and products made with unpasteurized milk can carry Listeria, as well as other dangerous bacteria, such as Salmonella and E. coli.

It’s very important to understand that, unlike most other foodborne bacteria, Listeria can grow at refrigerator temperatures (40 ˚F or below). That means the longer foods contaminated with Listeria are stored in the refrigerator, the more opportunity bacteria Listeria have to multiply. In addition, foods contaminated with Listeria can cross-contaminate surfaces they come into contact with – surfaces in the refrigerator and around the kitchen.

What can you do to protect yourself and your family from Listeria?

At-risk consumers and their caregivers should be aware of the foods that pose a higher risk for listeriosis:

High Risk Foods

  • Soft cheese made from unpasteurized (raw) milk.
  • Refrigerated smoked seafood and raw or undercooked seafood.
  • Cold or improperly heated hot dogs.
  • Sandwiches with cold deli or luncheon meat.
  • Raw or undercooked fish, such as sashimi, non-vegetarian sushi or ceviche.
  • Soft-boiled or “over-easy” eggs, as the yolks are not fully cooked.
  • Salads, wraps, or sandwiches containing raw (uncooked) or lightly cooked sprouts

Low Risk Foods

  • Hard or processed cheeses. Soft cheeses only if they are made from pasteurized milk.
  • Fully cooked fish or seafood.
  • Hot dogs reheated to steaming hot. If the hot dogs are served cold or lukewarm, ask to have them reheated until steaming, or choose something else.
  • Grilled sandwiches in which the meat or poultry is heated until steaming.
  • Fully cooked fish that is firm and flaky.
  • Fully cooked eggs with firm yolk and whites.
  • Salads, wraps, or sandwiches containing cooked sprouts.

If you are pregnant, find out which foods to avoid during pregnancy: Checklist of Foods to Avoid During Pregnancy

For more information on Listeria and Listeriosis see:

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