What is listeria?
Listeria is a bacterium [Listeria monocytogenes] that is common in the environment, and is carried by many farm animals and pets. You can be infected by listeria if you eat contaminated food. Some foods are riskier than others the riskiest are those eaten raw or inadequately cooked.
Listeriosis the name of the infection caused by listeria. It is rare, but potentially serious, especially for a fetus or newborn. Each year in Australia, about 150 people are hospitalised due to listeriosis, and a small number die.
Listeriosis symptoms
Many people exposed to listeria remain healthy. Some have no symptoms, while others have vomiting and diarrhoea, which is normally resolved without medical treatment.
But listeria can pass from the gut to other parts of the body such as the placenta and the brain. This type of listeria infection has a long incubation period [meaning it can take weeks or months after exposure for any symptoms to show].
Symptoms can be mild, including:
- mild fever
- muscle aches and joint pain
- headache
- diarrhoea
- nausea
- cough or cold
In rare cases, listeria can cause serious and life-threatening blood poisoning [septicaemia], meningitis [inflammation around the brain] or encephalitis [infection of the brain]. Symptoms of these serious conditions include:
- high fever
- stiff neck
- headache
- sleepiness and confusion
- seizures
Listeriosis in pregnancy and newborn babies
While listeriosis can affect anyone, it's particularly worrying for pregnant women because it can cause miscarriage, stillbirth or premature birth.
Newborn babies infected with listeria from their mother can become seriously ill with meningitis, blood poisoning or other infections. There are no records of women passing listeria to their babies through breastfeeding, however.
Listeria diagnosis
You should see your doctor if you think you might have listeriosis. For example, if you:
- have eaten food subject to a recall for listeria contamination, or
- are experiencing any symptoms of listeriosis
Your doctor will discuss the foods you've eaten and probably take a sample of blood. Listeriosis is confirmed if laboratory tests find listeria growing in the sample.
Listeriosis treatment
If you do develop listeriosis, you'll be treated with antibiotics. Prompt treatment can stop the infection from passing to your unborn baby.
Listeriosis prevention
The best way to avoid listeria infection is to avoid high-risk foods, and to follow hygienic food handling techniques.
Foods at high risk of carrying listeria include:
- foods at ready-to-eat salad bars, sandwich bars and delicatessens
- ready-to-eat meals
- soft and semi-soft cheeses
- unwashed raw vegetables
- soft-serve ice cream
- raw shellfish and seafood
- unpasteurised dairy products
- cold cured or prepared meats
- pâté
Click here for more information on food to avoid when pregnant.
Here are some tips on how to handle food to reduce your risk of infection.
- If you're cooking food, cook it thoroughly and eat it fresh.
- If you eat fruit and vegetables raw, wash them well first.
- Wash cookware and utensils well.
- Wash knives and cutting boards after handling uncooked foods.
- Store raw foods down low in the fridge and check the fridge temperature regularly.
- Refrigerate leftovers immediately. If you don't eat them within 24 hours, throw them out.
- If you do reheat them, make sure they're steaming hot.
- Thaw frozen meats in the fridge.
- Separate raw meat from vegetables, cooked foods and ready-to-eat foods in the fridge and while preparing food.
You should also:
- Look for 'best before' and 'use by' dates on packaged foods.
- Always wash your hands before handling food and after touching animals or visiting the toilet.
- Keep pets out of the kitchen, avoid touching faeces and wear rubber gloves under garden gloves.
When to seek help
Remember that even if you have only mild symptoms, listeria can have a serious effect on your baby. See your doctor if you have any concerns about listeria while pregnant.
You can also call Pregnancy Birth and Baby on 1800 882 436 to speak with a maternal child health nurse.
You should also seek medical advice if you have any concerns about the condition of your baby.