Food poisoning - listeria infection

What is listeria infection?

Listeria infection is an illness usually caused by eating foods contaminated by the Listeria monocytogenes bacteria.

Listeria infection (also known as listeriosis) is uncommon but it can cause death in at-risk people, such as the elderly and people whose immune systems are not working properly.

It is also a serious illness in pregnant women and their unborn babies.

Symptoms of listeria infection range from mild to severe

Early symptoms of listeria include:

• fever
• headache
• tiredness
• aches and pain.

These can lead to more serious problems, including:

• meningitis (brain infection)
• septicaemia (blood poisoning).

Listeria infection in pregnant women

Listeria infection can have severe consequences for pregnant women and their developing and newborn babies. Even a mild listeria infection can cause:

• miscarriage
• stillbirth
• premature birth
• a baby who is very ill when born.

Other people who are at high risk of listeria infection

People at high risk of listeria infection include:

• the elderly
• people whose immune system is weakened by illnesses like cancer, liver or kidney disease and diabetes
• people on medications like prednisone or cortisone. This includes organ transplant patients.

Listeria infection can be treated with antibiotics, but prevention is best

Early use of antibiotics can help in the treatment of listeria infection, but prevention is best.

Listeria high-risk foods

Listeria bacteria are common throughout the environment, including in soil, water and the digestive systems of animals. Unlike many bacteria, they can continue to multiply under refrigeration temperatures.

Refrigerated foods can become contaminated with the bacteria, which can then grow to dangerous levels under certain conditions.

Foods most commonly associated with Listeria include:

• foods with a long shelf-life that are kept under refrigeration
• foods that are eaten without any further treatment such as cooking that would kill the bacteria.

The following foods are considered high-risk for Listeria and should be avoided by at-risk people, including pregnant women:

• raw fruit, vegetables and herbs where washing procedures are unknown, including raw vegetable and herb garnishes
• ready-to-eat seafood that will not be further cooked – including smoked seafood (such as fish, mussels, and oysters), raw seafood (such as sashimi, sushi and oysters) and cooked/chilled seafood (such as peeled prawns)
• pre-prepared, pre-cut, or pre-packaged fruits and vegetables – including those available from greengrocers, supermarkets, buffets, salad bars and sandwich bars
• drinks made from fresh or frozen fruit and vegetables where washing procedures are unknown, such as juices and smoothies (excluding pasteurised or canned juices)
• cold meat products eaten without further cooking or heating, as commonly found in delis, sandwich shops or pre-packaged in supermarkets – such as pate, ham, salami, processed/fermented meat products, and cold pre-cooked chicken
• unpasteurised milk or foods made from unpasteurised milk
• soft-serve ice-creams
• soft cheeses – such as brie, camembert, ricotta, blue-vein, and feta
• refrigerated ready to eat dips – such as hummus, pesto, guacamole and tahini
• raw or lightly cooked sprouts – including green sprouts like alfalfa and bean sprouts
• sandwiches containing any of the high-risk ingredients mentioned above
• ready-to-eat foods – including leftover meats, which have been refrigerated for more than one day and will not be further reheated/cooked.

Hints for handling and preparing food

When you handle and prepare food, you should take care to:

• Wash and dry your hands well before preparing food, and between handling raw food and ready-to-eat foods.
• Wash raw fruit and vegetables thoroughly under running water before eating.
• Cook all foods of animal origin, including eggs, thoroughly.
• Don't use the same boards and knives for cooked foods that you used for raw foods unless they have been washed in warm, soapy water and dried.
• Defrost food by placing it on the lower shelves of the fridge or use a microwave.
• Always follow advice on food labels. Cooking foods before eating them can kill certain bacteria, including Listeria.

Store food with care

When you store food, you should:

• Keep food covered.
• Place cooked food in the fridge within one hour of cooking.
• Put raw meat, poultry and fish below cooked or ready-to-eat food in the fridge to prevent drips that could contaminate pre-prepared food.
• Do not use refrigerated foods beyond their use-by dates.
• Keep your fridge clean.

Food temperatures

Follow these tips on food temperatures:

• Your fridge temperature should be below 5 °C.
• Keep hot foods hot (above 60 °C) and cold foods cold (at, or below, 5 °C).
• Reheat food until the internal temperature of the food is piping hot.
• Ensure microwaved food reaches the desired temperature throughout before eating.

Where to get help

• In an emergency, always call triple zero (000)
• Your GP (doctor)
• NURSE-ON-CALL Tel. 1300 606 024 – for expert health information and advice (24 hours, 7 days)
• Food Safety Hotline Tel. 1300 364 352
• Food Standards Australia New Zealand Tel. (02) 6271 2222