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Hastings and Prince Edward Public Health

Listeriosis FAQs

What is Listeriosis?

Listeria monocytogenes (commonly known as listeria) is bacteria found in the environment. It is found in soil, plants, water, sewage and the feces of animals and humans. Listeria can cause Listeriosis, a serious but rare illness that in some cases can lead to brain infection and even death. Listeriosis is a rare disease in Canada. Animals and humans can carry the bacteria without knowing it. The elderly, newborns, pregnant women and those with a weak immune system can more easily become ill.

What causes it?

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

What are the symptoms?

Symptoms may start suddenly and include: vomiting, nausea, cramps, diarrhea, severe headache, constipation or fever. Some infections become severe and infect the brain or the lining of the brain or cause blood poisoning. Some people have only mild flu-like symptoms. Newborn babies may have loss of appetite, lethargy, jaundice, vomiting, skin rash and difficulty breathing.

When do symptoms start?

Symptoms can start from 3-70 days after eating contaminated foods, but usually within 3 weeks.

How do you test for Listeriosis?

A blood or spinal fluid test will determine if you have it. Contact your health care provider if you have symptoms, especially if they are severe.

How can I reduce the risk of infection?

  • Foods should be kept in the refrigerator at 4°C (40°F) or colder, or hotter than 60°C at all times. Foods should be always be refrigerated quickly.
  • Thoroughly cook raw meat such as beef, lamb, pork, or poultry.
  • Wash all raw fruit and vegetables before eating.
  • Avoid unpasteurized (raw) milk or foods made from unpasteurized (raw) milk.
  • Keep raw meat separate from vegetables, cooked foods, and ready-to-eat foods. Use 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.
  • Clean all utensils, cutting boards, and work surfaces with a mild bleach solution.
  • Follow ‘best before’ or expiry dates on food items.
  • If possible, buy only as much food as will be eaten in one or two days.


  • Heymann, D. L., (2008). Control of Communicable Diseases Manual. (19th Ed.). Washington, DC: American Public Health Association.
  • Ministry of Health & Long-Term Care, Listeria, March 2010.

Listeriosis Fact Sheet printable pdf

Need More Information About Listeriosis FAQs?

Talk to your health care provider or call our Communicable Disease Program at 613-966-5500 or 1-800-267-2803, ext. 349.

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