Pregnancy and food infections: Listeriosis and toxoplasmosis

Listeriosis and toxoplasmosis are types of food poisoning that rarely occur in healthy adults. However, pregnant women are more at risk of these infections because pregnancy causes changes to the immune system. If a pregnant woman contracts either of these infections, the consequences can be serious.

What are the signs of food poisoning?

Listeriosis can cause flu-like symptoms in pregnant women (e.g., fever, chills, fatigue, headaches, muscle or joint pain) and sometimes nausea, vomiting, cramps, diarrhea, or constipation. Symptoms usually appear 3 to 30 days after eating contaminated food, but in some cases, they can appear up to 70 days later.

In the case of toxoplasmosis, most infected people have no symptoms. When symptoms do occur, they are similar to those related to the flu or mononucleosis: aches, swollen lymph nodes, fatigue, headaches, fever, and sometimes sore throat.

Consequences of listeriosis and toxoplasmosis

If a pregnant woman contracts listeriosis, she may have a miscarriage, give birth to a stillborn baby, or deliver prematurely. The bacterium involved (Listeria monocytogenes) can be transmitted to the fetus and cause a serious brain or blood infection (encephalitis, meningitis, septicemia).

Toxoplasmosis can, in rare cases, be dangerous for the unborn baby. A pregnant woman can transmit the toxoplasmosis parasite to the fetus through the placenta. Probability of transmission is greater in the third trimester; however, consequences for the baby are more serious if the infection occurs in early pregnancy. The most severe cases of toxoplasmosis can lead to miscarriage, stillbirth, or serious health problems in surviving babies (e.g., seizures, enlarged liver or spleen, serious eye infections).

How can listeriosis and toxoplasmosis be prevented?

Certain foods are more likely to transmit listeriosis, toxoplasmosis, or other foodborne infections such as salmonella or E. coli. It’s therefore best to avoid consuming those foods during pregnancy.

Foods to avoid during pregnancy

• Raw or barely cooked eggs and any foods containing those ingredients (e.g., homemade Caesar dressing)
• Unpasteurized dairy products (e.g., milk, cheese made from raw milk)
• Soft cheeses (e.g., Brie and Camembert) and semi-soft cheeses (e.g., Saint-Paulin) as well as blue, feta, and creamy goat cheeses, even if they are made from pasteurized milk, as they can also transmit listeriosis
• Fresh fruits and vegetables that have not been washed
• Raw meat, such as tartare
• Raw fish and seafood, including shellfish and molluscs (oysters, clams). Sushi, sashimi, tartare, gravlax, and ceviche made from raw fish should also be avoided, as well as smoked fish if not cooked or reheated (e.g., smoked salmon).
• Undercooked meat, poultry, fish, or seafood, including smoked sausages or uncooked hot dogs
• Uncured deli meats, sliced prepared meats (such as ham for sandwiches), refrigerated pâtés and meat spreads
• Liver. Although an excellent source of iron, it contains too much vitamin A.
• Raw sprouts, such as alfalfa and bean sprouts
• Foods that are prepared at the grocery store and displayed in the ready-to-eat section (e.g., pasta salads, cooked chicken)
• Unpasteurized fruit or vegetable juices (e.g., apple cider), unless they are freshly squeezed by hand or made with an extractor, and consumed immediately
• Kombucha

For tips on how to eat well during pregnancy, consult our Healthy Eating During Pregnancy fact sheet.

Precautions to take in the kitchen

Whether you are pregnant or cooking for a pregnant woman, make sure you take the following precautions to prevent foodborne illnesses.

• Wash fruits and vegetables with water before eating them raw, cutting them, or cooking them. This includes fruits and vegetables that will be peeled, as the knife can carry bacteria from the surface of the peel to the inside.
• Use a vegetable brush to thoroughly clean fruits and vegetables that are eaten with the peel (e.g., apples, cucumbers, carrots).
• Wash herbs such as basil, rosemary, and thyme before adding them to dishes.
• Use a clean cloth or paper towel to dry washed food.
• Prevent raw meat from coming into contact with other foods.
• Thoroughly cook meat, fish, seafood, eggs, and sprouts before eating them.
• Serve food either hot or cold.
• Thaw food in the refrigerator, not at room temperature.
• Use different utensils, cutting boards, and plates to prepare and handle raw and cooked foods.
• Wash your hands and work surfaces with hot soapy water before cooking and after handling raw meat.
• Immediately clean up any leaks from meat products in the refrigerator.
• Change your kitchen towels often during the week.

Other suggested precautions to prevent toxoplasmosis

If you have a cat, it can carry toxoplasmosis and transmit it to you through its feces, so avoid cleaning the litter box yourself. If no one can do it for you, wear gloves and wash your hands thoroughly afterwards.

Since animal feces can also be buried in your garden, it is recommended that you wear gloves when gardening or when you have to touch soil or sand. For the same reason, it’s important to wash fruits and vegetables that have been in contact with soil.

Things to keep in mind

• Foodborne illnesses can have serious consequences, including death of the fetus, so it’s important to take every possible precaution.
• When you’re pregnant, it’s essential to wash fruits and vegetables well and to fully cook meat, fish, and eggs before eating them.
• Whenever possible, pregnant women should avoid cleaning cat litter boxes.

Scientific review: Stéphanie Côté, M.Sc., nutritionist Research and copywriting:The Naître et grandir team Updated: May 2019

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