What is listeriosis?
Listeriosis is a rare but potentially serious foodborne infection. It is caused by the bacteria Listeria monocytogenes. These bacteria are often found in the environment, particularly in soil, vegetation, and the feces of animals.
Listeriosis is most often caused by eating contaminated foods. A variety of foods can contain or become contaminated with Listeria, including unpasteurized dairy products, soft cheeses, deli meats, produce, and seafood products (e.g., smoked or candied salmon). Listeria can grow in foods that are wet, salty or sugary and can grow even when the food is refrigerated. Foods contaminated with Listeria often look, smell and taste normal. Listeriosis can also be transferred to a fetus during pregnancy or to a newborn during delivery.
What are the symptoms?
Listeriosis can start with flu-like symptoms, such as
- muscle aches;
- headache; and
Listeriosis can cause serious illness like meningitis, blood infection and even death. People at higher risk are more likely to get a serious illness. Listeriosis can also cause miscarriage or stillbirths in pregnant women or illness in newborn babies.
Who is at higher risk?
Pregnant women, newborn babies, older adults or those with weakened immune systems are at increased risk of getting a serious illness.
People at risk, who have symptoms, should speak to their health care provider.
If you are at risk, how can you protect yourself?
If you are at risk, you should either avoid or cook the following foods to steaming hot:
- soft and mould-ripened cheese such as Brie, Camembert, feta, gorgonzola;
- unpasteurized dairy products (e.g., milk and cheese);
- deli meats;
- hot dogs; and,
- refrigerated seafood products.
You can reduce the risk of listeriosis and other foodborne pathogens by following good food handling practices:
- cook raw foods of animal origin well (e.g., meat, seafood, poultry and eggs) to at least 74°C (165 °F) and avoid raw products (e.g., raw smoked salmon);
- keep the fridge at or below 4°C (40°F);
- wash raw vegetables before eating;
- keep uncooked meats separate from vegetables and other prepared foods;
- avoid unpasteurized milk, cheese and juice;
- wash hands, knives and cutting boards after handling uncooked foods;
- bag raw meat, poultry, or fish separately from other food items; and
- return home right away after shopping so that you can store all foods properly.
Listeria may grow slowly even at refrigeration temperatures, so if you are at risk, you should not keep food in the refrigerator for more than 3 days. All leftovers foods should be heated thoroughly to steaming hot before eating.
For More Information
For more information on food safety, see the following HealthLinkBC Files:
- HealthLinkBC File #59a Food Safety: Easy Steps to Make Food Safe
- HealthLinkBC File #76 Foods to Avoid for People at Higher Risk of Food-borne Illness
For more information about food safety during pregnancy, visit the BC Centre for Disease Control Pregnancy and Food Safety web page at www.bccdc.ca/health-info/food-your-health/food-safety.