What is Listeria infection?

Listeria infection or listeriosis is a rare, flu-like illness caused by eating food that contains the Listeria
monocytogenes bacteria. These bacteria are sometimes found in food that has not been properly prepared or stored, particularly in certain high risk food types. There are about seven cases of Listeria infection each year in Western Australia.

How do you get Listeria infection?

Most people think of listeriosis as an infection that affects pregnant women. However, due to the success of
educational campaigns targeting pregnant women, more than 90% of Listeria infections in WA now occur in
people who have weakened immune systems due to age, illness (e.g. diabetes, alcoholism) or treatment with steroids or other immunosuppressive medicines which are often prescribed for arthritis, cancer and after organ transplantation. Unfortunately, a large proportion of these people had consumed foods considered to be high risk for listeriosis because they were not aware that their illness or treatment made them more susceptible to this infection.

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What are the signs and symptoms of Listeria infection?

Listeriosis causes mild, ‘flu-like’ symptoms in healthy people. However, in people with weakened immune
systems, pregnant women and unborn babies, listeriosis can cause severe illness and death.
The infection usually occurs 3 weeks after eating contaminated food but the delay may be as long as two
months.

How do I get treated?

Listeria infection is easily treated with antibiotics. If you are in one of the high risk groups and develop a
flu-like illness with a fever, see your GP or a doctor of your choice as soon as possible. Patients with severe
Listeria infection usually require hospitalisation.

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How do I reduce the risks of getting Listeria infection?

Guide to safe preparation and storage of food for people at risk of Listeria infection:

Clean

• Always wash hands, knives and cutting boards with hot, soapy water before and after handling any raw food and between different kinds of foods.
• Keep your fridge clean, especially after any liquid spills.
• Always wash fruit and vegetables, especially before eating them raw.

Separate

• Keep raw food separated from cooked foods and ready-to-eat foods to avoid spreading bacteria.
• Always wrap or cover food to avoid contamination from bacteria.

Cook

• Listeria can be killed by heating. High risk foods and left-overs are safe to eat if heated until steaming hot and eaten straight away.
• Heat food for at least two or three minutes until it is steaming hot (above 60°C), all the way through.
• When using the microwave stop and stir the food a couple of times during heating. Microwaves heat food unevenly, so even if it seems to be piping hot, some parts of the food can still be cool and contain Listeria.
• Make sure meat and chicken are well cooked.

Chill

• Keep your fridge as cold as possible (below 5°C), without freezing the food.
• Refrigerate food, including leftovers, as soon as possible. Put them in the fridge as soon as they are cool enough to touch.
• Throw out food left at room temperature for long periods, especially in the summer. Be particularly
  careful during picnics and barbecues where food is often left in the heat. If in doubt, throw it out.
• Thaw frozen food in the fridge or microwave – never at room temperature.
• Avoid eating food which has been stored in the fridge for more than 24 hours; this includes home
  made food.

The key message to remember is make sure cooked foods are heated to steaming hot and eaten straight away.

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Where can I find more information on Listeria infection?

For further information contact your GP, a doctor of your choice or Health Direct (1800 022 222).