Being pregnant

How to keep the listeria bug at bay

Follow these simple guidelines to avoid listeriosis.

By Ellen Desjardins, M.H.Sc., RD, Public Health Nutritionist
Photo: iStock Photo: iStock

A bout of food poisoning is never pleasant, but most often there are no lasting after effects. Listeria is different.

Listeria is widespread in soil and water and on plants. Normally, healthy animals and people who ingest it through food don’t get sick. But if the immune system is weakened or changed, as it is in pregnancy, the bacteria can invade the bloodstream and cause listeriosis.

Pregnant women are about 20 times more likely than other adults to get listeriosis. Up to 20 days after exposure, a woman may have flu-like symptoms (chills, fever, sometimes diarrhea and upset stomach) or she may not have any symptoms. However, the bacteria can pass through the placenta and lead to health problems for the baby or even cause miscarriage or preterm birth.

Ominous as this may be, there are steps you can take to minimize the risk. Listeria in milk, poultry, fish or meat is destroyed by pasteurization or thorough heating. Therefore, do not eat soft-ripened cheeses — brie, camembert, blue cheese, feta — and thoroughly cook poultry, fish or meat. (Hard and semi-soft cheese like mozzarella, cheese slices, cottage cheese, cream cheese, and yogurt, are safe.) Wieners, sausages, deli meats and smoked fish may be contaminated after processing. Heat these foods to a steaming temperature before eating.

If you have questions about specific foods, call your local health department. If you have symptoms, consult your doctor. Listeriosis can be treated with antibiotics.


Cook Thoroughly:

• meat, fish, poultry, wieners, sausages, deli meats, smoked fish

Separate the above foods from other foods during storage or preparation to avoid cross-contamination.


• soft-ripened cheese such as brie, camembert, blue cheese, feta • unpasteurized milk or foods made with unpasteurized milk • meat or fish spreads or pâtés



• wash hands frequently when handling food • wash raw vegetables thoroughly • keep knives and cutting board surfaces clean • clean the fridge regularly • wipe spills with hot water and soap

Chill or Freeze:

• refrigerate or freeze foods promptly after buying • keep the fridge below 4°C


Discard foods that have passed their expiry date or that have been left at room temperature longer than two hours

This article was originally published on Dec 14, 2004

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