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​Listeriosis is a food-borne illness that is caused by the bacterium listeria monocytogene.  It affects around 1,600 people each year. Listeria is most likely to infect pregnant women, their newborns, adults 65 and older and people with weakened immune systems.

Causes of Listeriosis

Foods that can be contaminated with listeria include:

  • Soft cheeses made with unpasteurized milk
  • Raw sprouts
  • Melons
  • Hot dogs, pâtés, lunch meats or cold cuts
  • Smoked seafood


Like other food-borne infections, listeria causes fever, diarrhea and occasionally vomiting or headaches. In cases of invasive listeriosis in which the bacterium moves beyond the gastrointestinal (GI) tract, symptoms vary depending on whether you are pregnant.

Pregnant women may experience:

  • Flu-like symptoms such as fatigue and muscles aches
  • Trouble with the pregnancy, including miscarriage, premature birth, still birth or life-threatening infection in the newborn

People other than pregnant women may experience:

  • Headache
  • Fever
  • Muscle aches
  • Stiff neck
  • Confusion
  • Loss of balance
  • Convulsions

Invasive infections require hospital care, as one in five cases proves fatal. Listeriosis causes fetal loss in approximately 20% of pregnancy cases.

Illness and Injury