Nutrition and Health

By Melissa Bess

Listeria has been in the media lately because it has been the source of national food borne illness outbreaks. Listeria is caused by eating food contaminated with the Listeria monocytogenes bacteria. It usually affects older adults, women who are pregnant, newborns, or those with compromised immune systems. These groups are high-risk and account for 90% of Listeria cases.

The Listeria bacteria is found in nature, both in soil and water. Animals can carry Listeria and then contaminate foods of animal origin, such as meat or dairy products. Listeria can contaminate food processing facilities and live there for years. Humans get sick by eating contaminated foods.

Listeria can be found in: uncooked meats, vegetables, raw milk, cheese and other products made from raw milk, soft cheeses, pre-packaged salads, refrigerated pre-cooked seafood, raw sprouts, pate or meat spreads, and some ready-to-eat meats (hot dogs and deli meats).

To minimize risk of Listeria, make sure you follow these steps:

  • Wash hands before all food preparation and before eating.
  • Wash all fruits and vegetables before consumption (this includes those that will be peeled, like bananas). Scrub melons with a small brush.
  • Avoid raw or unpasteurized milk or products made from raw or unpasteurized milk.
  • Separate uncooked meats from vegetables, cooked foods, or ready-to-eat foods.
  • Keep your kitchen clean.
  • Refrigerate leftovers within two hours of preparation.
  • Use a food thermometer to cook meat to a safe temperature.
  • Keep your refrigerator at 40 degrees F or below. The dangerous thing about Listeria is that it can grow in the refrigerator in some foods.

If you are pregnant, over 65 years old, or have a compromised immune system, here are additional safety tips:

  • Do not eat hot dogs or deli meats unless they have been heated to 165 degrees F.
  • Avoid pre-packaged salads or ready-to-eat salads from the deli counter. It would be safer to make your own version of these at home.
  • Avoid raw sprouts.
  • Avoid soft cheese such as feta and brie unless the label says it has been made with pasteurized milk.
  • Avoid refrigerated pate or meat spreads. Avoid cold cooked chicken. Make your own at home.
  • Do not eat refrigerated smoked seafood or chilled pre-cooked seafood (such as shrimp cocktail). Canned, frozen, or shelf stable seafood is safe.

For the higher risk groups, it would be best to avoid pre-prepared cold meats and seafood, cold deli meats, cold hot dogs, and pre-prepared salads from a deli counter, salad bar, or buffet. Make your own versions of these salads at home.

Symptoms of Listeria infection include fever, muscle aches, and sometimes include gastrointestinal symptoms. Symptoms vary with each infected person. If someone thinks they have been infected with Listeria, they should seek medical attention immediately. Listeria may not occur for weeks after eating contaminated food. It is treated with antibiotics. Even with prompt treatment, some Listeria cases can lead to death, especially in high-risk groups. The CDC has more information on their website at

If you have questions, please contact Melissa Bess, Nutrition and Health Education Specialist with University of Missouri Extension. Call the Camden County Extension Center at 346-2644, stop by our office at 44 Roofener Street, Camdenton, or email Melissa at