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Listeriosis Fact Sheet

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Listeriosis is a serious infection caused by the bacterium Listeria monocytogenes

Listeriosis is a rare disease. Persons at higher risk for disease include:

  • Pregnant women
  • Newborns
  • Elderly persons
  • Individuals with a weakened immune system (for example: persons with AIDS, cancer, diabetes, or kidney disease)

Listeria is commonly found in the environment

Listeria is found in dust, soil, water, sewage, and silage, and it is a known cause of disease in animals. It has also been found in various meats, vegetables, seafood, and dairy products. Listeria can multiply in refrigerated food that is contaminated. Pasteurization of dairy products and proper cooking are usually adequate to kill the bacteria. In addition, the bacteria can also live in the gastrointestinal tract of some individuals who are infected, but do not have symptoms.

Listeria is spread by ingestion of contaminated foods, direct contact with infected animals, or from a pregnant mother to her baby

Infected individuals may spread the bacteria to others for up to several months.

Symptoms can be mild in healthy individuals, but are more severe in those with weakened immune systems

Symptoms may include fever, muscle aches, and 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. After exposure, symptoms usually occur within 3 days to 10 weeks, but most often within 3 weeks.

Pregnant women who become infected generally only develop flu-like symptoms (fever, tiredness, achiness). However, the infection can cause premature labor, premature delivery, miscarriage, or stillbirth.

Newborns born to infected mothers can develop listeriosis within one week of birth (called early-onset) or after several weeks. Infants with early-onset disease usually develop severe blood infections (sepsis), pneumonia, or skin rashes. These infants are at highest risk of death.

If you think you have listeriosis, you should see a doctor immediately

Listeriosis is treated with antibiotics

Listeriosis can be prevented

  • Keep uncooked meats separate from vegetables, cooked foods, and ready-to-eat foods.
  • Thoroughly cook foods from animal sources, such as beef, pork, or poultry.
  • Avoid unpasteurized milk, or foods made from unpasteurized milk.
  • Wash raw vegetables thoroughly before eating.
  • Wash hands, knives, cutting boards, and other contaminated surfaces after contact with uncooked foods.
  • Individuals at high risk may choose to avoid soft cheeses, pâté, and ready-to-eat processed meat products such as deli meats.