Listeria is a type of bacteria that can cause a serious illness (listeriosis) in pregnant women.

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.

Who is at risk?

Pregnant women, their babies, people with a lowered immune system and the elderly are most at risk from listeria infection. Almost all other people are not harmed by it. Listeria monocytogenes can be transmitted by eating infected food. The bacteria have been found in a variety of foods at all stages of preparation, and can still grow on food that is stored in a fridge.

Although pregnant women are at increased risk from Listeria infection, it’s important to remember that the risk of listeriosis in Australia is low, and that there are simple steps you can take to avoid infection while still eating a balanced, healthy diet.

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.

Symptoms may include:

  • mild fever;
  • headache;
  • diarrhoea;
  • nausea;
  • 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.

Listeria can also sometimes cause an infection of the brain (encephalitis) or meningitis, causing symptoms such as fever, headache, stiff neck, 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.

What are the complications of listeriosis?

Pregnancy complications

If a pregnant woman develops listeriosis, it can cause miscarriage, premature labour, or a stillbirth.

Listeriosis in newborns

Newborn babies who develop listeriosis can develop a chest infection, blood poisoning (sepsis), or an inflammation of the membranes surrounding the brain (meningitis).

When to see your doctor

You should see your doctor if you are experiencing any symptoms, or if you are concerned that you may have eaten a contaminated food (such as a food that has been recalled due to listeria contamination).

Your doctor will ask about your symptoms and perform a physical examination. They will also ask about the foods you have recently eaten.

A blood test can be used to determine whether you have listeriosis.

Treatment

Early treatment with antibiotics can help prevent complications of listeriosis in pregnant women.

Babies with listeriosis can also be treated with antibiotics.

How do I avoid listeriosis?

Eating a healthy, balanced diet is important during pregnancy. Making informed and sensible food choices reduces the risk of listeria infection.

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 and cut up at home.
  • 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

The following foods should be avoided during 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.
  • Sliced, ready-to-eat cold meats (either packaged or from a deli or sandwich bar).
  • Uncooked seafood, such as oysters, sushi, sashimi or smoked salmon.
  • Stored salads and coleslaws, especially from delicatessens or supermarkets.
  • Pre-cut fruit and un-pasteurised juices.
  • Seed sprouts.
  • Raw (unpasteurised) milk or foods made from raw milk.
  • Soft, semi-soft and surface-ripened cheeses, such as brie, camembert, feta, ricotta 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

Follow these tips on safe food handling to reduce Listeria risk.

  • 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.
  • Promptly refrigerate left-over food and use within one to 2 days.
  • 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.

Do I need to avoid certain foods while breast feeding?

After you have had your baby you are no longer at increased risk of listeriosis, and there is no evidence that listeria can be passed to babies through breast feeding. So you don’t need to restrict your diet once your baby is born.

Last Reviewed: 10/02/2016

myDr



References

1. NSW Food Authority. Listeria and pregnancy (Jan 2014). http://www.foodauthority.nsw.gov.au/_Documents/foodsafetyandyou/listeria_and_pregnancy.pdf (accessed Feb 2016).
2. Food Standards Australia New Zealand. Listeria and food (updated Jul 2012). http://www.foodstandards.gov.au/consumer/safety/listeria/pages/factsheet/listeriaandfoodjuly25590.aspx (accessed Feb 2016).
3. Centers for Disease Control and Prevention (CDC). Listeriosis (Listeria) and Pregnancy (updated 1 Dec 2011). (accessed Feb 2016).