What is it?

Listeria monocytogens is a gram positive bacteria that is found in the intestines of animals and man as well as in the soil. It is noted that it can survive freezing drying and heat quite well.

What are the symptoms?

Normal healthy people rarely show Listeria’s symptoms (nausea, cramps, diarrhea, headache, constipation fever).
The young, elderely or those with a compromised immune system are at the highest risk. Symptoms appear usually 2 to 30 days after eating the contaminated food. Flu like symptoms can be followed by brain or blood infections which can lead to death.
Women (who develop listeriosis) within their first three months of pregnancy may miscarry or if later in the pregnancy the baby may be still born or very ill.

Foods associated with L. monocytogenes

Raw milk, cheeses (particularly soft-ripened varieties), ice cream, raw vegetables, fermented raw-meat sausages, raw and cooked poultry, raw meats (all types), and raw and smoked fish.
L. monocytogenes can grow at temperatures as low as 3°C which can allow for the growth of the microorganism in the refrigerator.

L. monocytogenes is easily spread by contact with an infected product or surfaces (hands, food contact surfaces).

How do you avoid getting sick?

Keep hot foods hot (above 60°C/140°F) and cold foods cold (4°C/40°F or lower).

Cook foods until they are steaming hot (See our fact sheet on the proper use of thermometers to check internal temperatures)

Avoid unpasteurized milk and food made from it (ie raw milk cheese)

Avoid storing foods for long periods (buy only enough product that will be consumed in a day or two)

Wash raw fruits & vegetables thoroughly before eating.

Wash hands before, during and after handling any type of food, especially raw meat and poultry.

Clean all utensils, cutting boards and work surfaces with a mild bleach solution (5 ml/1 tsp. bleach per 750 ml/3 cups water) before and after using.

Separate utensils for raw and cooked foods.

Follow “use by” dates especially on packaged goods with a long shelf life.

If you are pregnant or have a weakened immune system

The high risk group for L. monocytogenes are pregnant women and their fetus, persons immunocompromised by corticosteroids, anticancer drugs, graft suppression therapy, AIDS & cancer patients as well as the elderly.

Soft cheeses are of more a concern and should be avoided (Brie, feta, Camembert) whereas hard cheese, processed cheese cream and cottage cheese and yougurt can be eaten safely while pregnant.

Avoid refrigerated pâtés.

The risk of deli meats may be low however people in this high risk category could choose to avoid eating these foods or that theyt are heated to 74°C (165°F).

Avoid refrigerated smoked fish products (unless they are cooked prior to eating)