What it is:

Listeriosis is a serious infection caused by eating food contaminated with the bacterium Listeria monocytogenes and has recently been recognized as an important public health problem in the United States. 


A person with listeriosis usually has fever, muscle aches, and sometimes gastrointestinal symptoms such as nausea or diarrhea. If infection spreads to the nervous system, symptoms such as headache, stiff neck, confusion, loss of balance, or convulsions can occur.

Infected pregnant women may experience only a mild, flu-like illness; however, infection during pregnancy can lead to premature delivery, infection of the newborn, or even stillbirth.

Associated foods:

  •  Listeria monocytogenes is found in soil and water, so vegetables can become contaminated from the soil or from manure used as fertilizer. 

  • Animals can carry the bacterium without appearing ill and can contaminate foods of animal origin such as meats and dairy products.

  •  The bacterium has been found in a variety of raw foods, such as uncooked meats and vegetables, as well as in processed foods that become contaminated after processing, such as soft cheeses and cold cuts at the deli counter.

  •  Unpasteurized (raw) milk or foods made from unpasteurized milk may contain the bacterium.

  •  Listeria is killed by pasteurization, and heating procedures used to prepare ready-to-eat processed meats should be sufficient to kill the bacterium; however, unless good manufacturing practices are followed, contamination can occur after processing.


  •  General recommendations:

  •  Cook thoroughly raw food from animal sources, such as beef, pork, or poultry.

  •  Wash raw vegetables thoroughly before eating.

  •  Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods.

  •  Avoid raw (unpasteurized) milk or foods made from raw milk.

  •  Wash hands, knives, and cutting boards after handling uncooked foods.

  •  Recommendations for persons at high risk, such as pregnant women and persons with weakened immune systems, in addition to the recommendations listed above:

  •   Avoid soft cheeses such as feta, Brie, Camembert, blue-veined, and Mexican-style cheese. (Hard cheesed, processed cheeses, cream cheese, cottage cheese, or yogurt need not be avoided.)

  •   Cook until steaming hot left-over foods or ready-to-eat foods, such as hot dogs, before eating.

Although the risk of listeriosis associated with foods from deli counters is relatively low, pregnant women and  immunosupressed persons may choose to avoid these foods or thoroughly reheat cold cuts before eating.


Even with prompt treatment, some infections result in death. This is particularly likely in the elderly and in persons with other serious medical problems. When infection occurs during pregnancy, antibiotics given promptly to the pregnant woman can often prevent infection of the fetus or newborn.  Babies with listeriosis receive the same antibiotics as adults, although a combination of antibiotics is often used until physicians are certain of the diagnosis.

People at risk:

  •  Pregnant women – They are about 20 times more likely than other healthy adults to get listeriosis.

  •  Newborns – Newborns rather than the pregnant women themselves suffer the serious effects of infection in pregnancy. 

  • Persons with weakened immune systems 

  • Persons with cancer, diabetes, or kidney disease

  •  Persons with AIDS – They are almost 300 times more likely to get listeriosis than people with normal immune systems.

  •  Persons who take glucocorticosteroid medications

  •  The elderly