What is listeriosis?

Listeria is a bacteria that can cause a rare but serious illness called listeriosis. Pregnant women, the elderly, and those with a weakened immune system have a higher risk of becoming seriously ill.​

What are the signs and symptoms?

Sign and symptoms usually start 3 to 70 days after exposure and include:

  • Vomiting
  • Nausea
  • Cramps
  • Muscle aches
  • Diarrhea
  • Severe headache
  • Constipation
  • Persistent Fever

In serious cases, the bacteria can spread into the nervous system, brain, or blood causing infections and symptoms can include:

  • Stiff neck
  • Confusion
  • Loss of balance

What are the complications?

Pregnant women, the elderly, and people with weakened immune systems face a higher risk of becoming seriously ill with listeriosis. During pregnancy listeriosis infection can cause premature labour, miscarriage, stillbirth, a low-birth weight infant, or life-long problems for the baby, such as mental retardation, paralysis, seizures, blindness, and impairment of the brain, heart, or kidney.

If you're pregnant, elderly, or have a weakened immune system:

Don't drink...
  • Raw (unpasteurized) milk and foods made with unpasteurized milk.
Don't eat...
  • Soft cheese such as Feta, queso blanco, queso fresco, Brie, Camembert, blue-veined cheeses, and Panela unless it is made with pasteurized milk. Make sure the label says “Made with pasteurized milk.
  • Refrigerated pate, meat spreads from a meat counter, or smoked seafood in the refrigeration section of the store.
  • Hot dogs, luncheon meats, bologna, or other deli meats unless they're reheated until steaming hot.
  • Salads made in the store like ham salad, tuna salad, or seafood salad.

How is it spread?

Listeria is widespread in the environment and can be found in soil, vegetation, water, sewage, silage and in the stool of humans and animals, sometimes without knowing. Listeria bacteria have been found in a variety of raw foods, such as uncooked meats and vegetables.

By drinking...

  • Unpasteurized milk or by eating unpasteurized cheese. Milk, cheeses, and other foods made from unpasteurized milk are likely to contain the bacterium.

By eating...

  • Meat and poultry that’s undercooked.
  • Plants and vegetables, that have been contaminated by contaminated soil, water, and/or manure-based fertilizer.
  • Foods that have become contaminated during food preparation in the kitchen or in the food processing plant. Listeria bacteria have been found in foods that become contaminated after cooking or processing, such as soft cheeses and processed meats such as hot dogs, deli meat, and smoked seafood.

Is there treatment?

You need to drink plenty of fluids and keep yourself hydrated.

Antibiotics can effectively treat the infection, but early diagnosis can be critical to the success of the treatment, especially for those at high risk (i.e., pregnant women, the elderly, and people with weakened immune systems).

There's no vaccine to prevent infection. See your health care provider if symptoms appear.

Preventing Infection

  • Rinse all raw produce, such as fruits and vegetables, before eating, cutting, or cooking. Fruits and vegetables should still be thoroughly rinsed even if they will be peeled.
  • After handling foods, especially raw foods like meat and fish, thoroughly clean and sanitize all surfaces and utensils, including cutting boards, used for food preparation with a kitchen sanitizer (following the directions on the container), or use a bleach solution (5 mL household bleach to 750 mL water), and rinse with water.
  • Listeria can grow in foods in the refrigerator. Use a thermometer to check the temperature in your refrigerator. Make sure it is at 4°C (40°F). As the storage temperature increases, so does the growth of listeria in foods.
  • Cook meats and poultry thoroughly. Use of a meat thermometer is recommended.
  • Wear gardening gloves and wash hands when gloves are removed.

Health Care Providers

Listeriosis is a reportable disease to the Medical Officer of Health. Laboratories are required to fax lab confirmed case information to the Health Unit at fax number 226-783-2132.

If you have any questions or concerns during working hours, please call 519-258-2146 ext.1420 or after hours, weekends and holidays at 519-973-4510.