What is listeria?
Listeriosis is a comparatively rare form of foodborne illness, but it can be a very serious disease in pregnant women, people who have diabetes, cancer or suppressed immune systems, and the elderly over 70 all of whom will need to avoid the foods listed below. It has also caused occasional outbreaks of mild gastroenteritis in healthy people.
The symptoms are usually described as ‘flu-like’, although vomiting and diarrhoea can occur. Miscarriage can result if a pregnant woman is infected, even if she doesn’t show the symptoms. The time from infection to symptoms can be anywhere between 8 to 90 days.
Listeria is widely found in the environment so most raw foods are likely to be contaminated. Listeria is easily killed by heat, although cooked foods can easily become re-contaminated through poor food handling after cooking.
This is one of the few pathogens that can grow in the refrigerator, so ready to eat food should never be stored in the fridge too long. Although it can grow in the fridge, it will do so only very slowly so make sure your refrigerator is keeping your food at or less than 5°C. Never eat packaged, ready to eat food, such as those listed below, after their ‘use by’ or ‘best before’ date.
How to avoid Listeria?
If you (or someone in your household) has a weakened immune system, is over 70 or is pregnant, the best way to avoid Listeria is to eat freshly cooked or freshly prepared food.
Try to avoid foods which have a higher risk of Listeria contamination such as:
- cold meats from delicatessen counters and sandwich bars, and packaged, sliced ready-to-eat meats
- cold cooked ready- to-eat chicken (whole, portions, or diced)
- pre-prepared or pre-packaged fruit or vegetable salads, including those from buffets and salad bars
- pre-packaged, cut fruit or vegetables
- frozen fruit and vegetables that are eaten raw without cooking eg berries, corn kernels
- chilled seafood such as raw oysters, sashimi and sushi, smoked ready-to-eat seafood such as smoked salmon and cooked ready-to-eat prawns
- soft, semi-soft and surface-ripened cheeses such as brie, camembert, ricotta, blue and feta
- refrigerated paté or meat spreads
- soft serve ice cream
- unpasteurised dairy products
- sprouted seeds/bean sprouts.
You can further reduce your risk of listeriosis by following these food safety tips:
- avoid foods that are past their ‘best before’ or ‘use by’ date
- refrigerate leftovers promptly and use within 24 hours, or freeze
- cook foods thoroughly
- reheat foods until it is steaming hot
- check this advice from Food Standards Australia New Zealand on making safer food choices.and this useful list of foods to avoid and alternatives from the NSW Food Authority.
For more information about listeriosis see Healthdirect
The Cancer Council has a range of useful publications for people with cancer, their family and friends
Watch this short video about listeria
Who is most at risk?
People at higher risk of listeriosis include pregnant women, their unborn and newborn babies, the elderly over 70, diabetics and other people whose immune systems have been weakened by illness or drugs (for example: cancer patients, organ transplant recipients, and people on drugs like cortisone).