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Listeria monocytogenes Infection (cont.)

What causes listeriosis?

Listeriosis is a disease caused by infection with a gram-positive, rod-shaped bacterium called Listeria monocytogenes.

  • Listeria monocytogenes is ubiquitous, and it is usually found in soil, water, and decaying vegetation. Many farm animals and other domestic and wild animals can harbor the bacterium. Though many of these animals may be asymptomatic carriers of the bacterium, they can serve as a source to contaminate the foods produced from them, such as meat and dairy products. Listeria monocytogenes may also enter food-processing factories and contaminate food contact surfaces and non-food contact surfaces (for example, floors or drains).
  • Listeria monocytogenes may contaminate various foods and dairy products, for example, raw vegetables and fruits, uncooked meats, packaged and processed meats (for example, hot dogs or deli meats), smoked seafood, soft cheeses, and unpasteurized milk/dairy products.
  • Listeriosis is most often a food-borne illness that is transmitted to humans after they ingest foods or liquids contaminated with Listeria monocytogenes.
  • Human-to-human transmission occurs when an infected pregnant mother transmits the infection to her fetus/newborn via the placenta or during delivery.
  • In 2011, contaminated cantaloupes from a Colorado farm caused 146 cases of listeriosis with 32 fatalities, making it the deadliest food-borne illness outbreak in the United States since the early 1900s.

What are the risk factors for listeriosis?

Listeriosis is a disease that rarely affects healthy individuals. However, several risk factors do exist for acquiring and developing listeriosis.

  • Eating or drinking food products contaminated with Listeria monocytogenes is the greatest risk factor for developing listeriosis.
  • Certain patient populations are at greater risk for developing listeriosis:
    • Newborns
    • Elderly
    • Pregnant women
    • Individuals with a poorly functioning immune system (for example, patients with AIDS, cancer, diabetes, chronic kidney disease, alcoholics, or those taking immunosuppressive medications)
Medically Reviewed by a Doctor on 11/20/2017
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