Listeriosis

Fact Sheet Adobe Portable Document Format (PDF)27KB

What is Listeria?

  • Listeria monocytogenes (commonly known as Listeria) is a bacterium that is widespread in the environment.
  • It is found in soil, vegetation, water, sewage and the feces of animals and humans.
  • Listeria can cause listeriosis, a serious but rare illness that in certain cases—usually in those with other debilitating illnesses—can lead to more serious infection and even death.

top of page

What causes listeriosis?

  • Listeriosis is caused most often by eating food contaminated with Listeria bacteria.
  • Listeria can be found in unpasteurized (raw) dairy products, raw vegetables and uncooked meats.
  • Foods can also be contaminated after processing, such as hot dogs, cold cuts or deli meats.
  • Unlike most other harmful bacteria, Listeria can grow on foods stored in a refrigerator.
  • Foods contaminated with Listeria look, smell and taste normal.
  • Listeria can be killed by proper cooking procedures.
  • Listeria bacteria are not commonly passed from person to person.

top of page

What are the symptoms of listeriosis?

  • Symptoms may start suddenly and include:
    • vomiting
    • nausea
    • cramps
    • diarrhea
    • severe headache
    • constipation or fever
  • Some infections become severe and can develop into an infection of the brain or the lining of the brain, or blood poisoning.
  • Some people experience only mild, influenza-like symptoms.
  • Symptoms can occur from 3 - 70 days after eating foods contaminated with Listeria.
  • Many animals as well as up to 1 in 10 people may be carriers of Listeria, harbouring the bacteria in their large intestines but not showing any signs of illness. Few will actually develop listeriosis.
  • Listeriosis is a relatively rare disease in Canada.

top of page

How does one test for listeriosis?

  • A blood or spinal fluid test may help to determine if you have listeriosis.
  • Contact your health care provider if you have symptoms , especially severe symptoms.

top of page

Who is at risk?

  • Pregnant women have a higher risk of listeriosis than other healthy adults. If a pregnant woman develops listeriosis during the first 3 months of her pregnancy, she may miscarry. Up to 2 weeks before a miscarriage, pregnant women may experience:
    • a mild, influenza-like illness with chills, fatigue, and headache
    • muscular and joint pain
  • Listeriosis later on in the pregnancy can result in a stillbirth or the birth of an acutely ill child.
  • The elderly are more prone to severe illness as risk increases with age.
  • People with weakened immune systems are more at risk including those undergoing chemotherapy, transplant patients, and those with AIDS, diabetes or alcoholism.

top of page

What should I do if I have food that has been recalled because of Listeria contamination?

  • Throw out food that has been recalled because of Listeria contamination.
  • See the Canadian Food Inspection Agency (CFIA) website for the most current list of food recalls  External Link .
  • If you have eaten a contaminated product and do not have any symptoms, no tests are required. However, if you become ill with fever or serious illness, contact your health care provider and mention your possible exposure.

top of page

How can I reduce the risk of listeriosis infection?

  • Foods should be kept out of the temperature danger zone (between 4 - 60°C or 40 - 140°F). Keep the refrigerator at 4°C (40°F) or colder. Foods should be refrigerated promptly.
  • Thoroughly cook raw meats such as beef, lamb, pork, or poultry.
  • Wash raw vegetables and fruit before eating.
  • Avoid unpasteurized (raw) milk or foods made from unpasteurized (raw) milk.
  • Keep raw meats separate from vegetables, cooked foods, and ready-to-eat foods including using separate cutting boards for raw meat and foods that are ready to eat.
  • Wash Your Hands  before and after preparing food and after handling animals.
  • Follow ‘best before’ or expiry dates on food items.

top of page

Foods at Higher Risk include:

  • Hot dogs, especially straight from the package without further heating. The fluid within hot dog packages may contain more Listeria than the hot dogs. Avoid spreading fluid from packages onto other foods, cutting boards, utensils, dishes and food preparation surfaces.  Wash Your Hands after handling hot dogs.
  • Deli-meats
  • Soft and semi-soft cheeses such as feta, brie, camembert and blue-veined cheese if they are made from unpasteurized milk
  • Refrigerated pâté and meat spreads
  • Refrigerated smoked seafood and fish
  • Raw or undercooked meat, poultry and fish

top of page

top of page