Listeria risk in pregnancy
Listeria bacteria are widely found in dust, soil, water, plants, sewage and animal droppings. Listeria monocytogenes is a specific type of Listeria that can cause infection in humans (listeriosis), mainly through contaminated food.
How does Listeria affect humans?
Listeriosis is most dangerous to pregnant women, their babies, people with a lowered immune system and the elderly. Almost all other people are not harmed by it. If a pregnant woman develops listeriosis, it can cause miscarriage, premature labour, or a stillbirth. Newborn babies who develop listeriosis can develop a chest infection, blood poisoning (sepsis), or an inflammation of the coverings of the brain (meningitis). This can sometimes cause death.
What are the symptoms of listeriosis in pregnant women?
Listeriosis may cause no symptoms at all or you may feel like you have a mild dose of the flu. The symptoms may include a mild fever, headache, diarrhoea, nausea, vomiting, aches and pains in your joints and muscles or a mild cough or cold. Some women can become very sick with listeriosis and have a very high temperature. This increases the risk of an unborn child being infected. Listeria can also sometimes cause an infection of the brain (encephalitis) or meningitis, causing symptoms such as fever, headache, confusion and seizures. Fortunately, serious listeriosis in pregnant women and their babies remains a rare condition; however, it is possible that many milder cases go unnoticed.
How are pregnant women infected by Listeria?
Listeria monocytogenes can be transmitted to pregnant women by infected food. The bug has been found in a variety of foods at all stages of preparation, from raw to well-cooked left-overs and will still grow on food that is stored in a fridge.
How do I avoid listeriosis?
The following foods should be safe to eat during pregnancy.
- Most foods that have been thoroughly cooked (until piping hot) and eaten straight away.
- Vegetables and fruit that have been well washed.
- All tinned foods.
- Breads and cereals (without added mock creams or custards).
- Dried food (such as fruit, nuts, lentils, beans).
- Pasteurised milk.
- Pasteurised cheeses. Cream cheese and plain cottage cheese are safe.
Do not eat the following foods in pregnancy
- Chilled, pre-cooked seafood products, unless re-heated as above and eaten hot.
- Pâté, pre-cooked chicken, ham and other chilled pre-cooked meat products.
- Uncooked seafood, such as oysters or smoked salmon.
- Stored salads and coleslaws, especially from delicatessens or supermarkets.
- Raw (unpasteurised) milk or foods made from raw milk.
- Soft, semi-soft and surface-ripened cheeses, such as brie, feta or blue veined cheeses.
- Soft-serve ice cream and any products containing this type of ice cream, such as some thick shakes.
Safe ways to handle food at home
- Keep uncooked meats separate from vegetables and from cooked foods and ready-to-eat foods. Uncooked meats should also be well wrapped or covered.
- Wash hands, knives, and cutting boards thoroughly with hot water and soap after handling uncooked foods.
- Cook left-over foods or ready-to-eat foods, such as hot dogs, until steaming hot before eating. (Food should be reheated to at least 74 degrees Celsius for 2 minutes to kill Listeria bacteria.)
- When using a microwave, take special care to heat foods all the way through until they are piping hot.
- Wash all fresh food carefully before eating it.
Last Reviewed: 23 August 2009
- 1. Food Standards Australia New Zealand. Listeria and food: commonly asked questions [published 2005, Dec; accessed 2009, Sep 18]. Available at: http://www.foodstandards.gov.au/newsroom/factsheets/factsheets2005/listeriacommonlyaske3115.cfm
