Listeria infection has been in the news recently. However, it’s important to remember that it is is rare, is caused by eating foods contaminated by the bacteria and is not usually transmitted between people.
The overall number of cases reported in Australia each year has been about 65, with between 1 to 14 confirmed cases of listeriosis reported in pregnant women each year for approximately 300 000 births.
Foods associated with infection include unpasteurised milk, dairy products made from unpasteurised milk, soft cheeses including ricotta and fetta, juices, soft serve ice-cream, tofu, tempeh, sushi, seed sprouts, chilled ready-to-eat foods like pre-packed sandwiches, pate and deli meats, pre-cut fruit, oysters, packaged salads, cold ready-to-eat chicken, sashimi, smoked salmon. And, most recently, rockmelon (grown in the Eastern States) due to soil contamination on the skin of the fruit.
Listeria infection can be dangerous to those with weakened immune systems ( the elderly, those with cancer, diabetes, liver and kidney disease) and to pregnant women and their unborn babies. Symptoms range from fatigue, headache, diarrhoea, aches and fever to meningitis and septicaemia. The symptoms occur from as early as a few days to several weeks, usually three weeks. The diagnosis is made using a blood or spinal fluid sample
There are simple guides to avoid infection including advice about food preparation, handling and storage:
– washing hands before preparing food and between raw and ready-to eat foods
– defrosting food in the fridge or microwave
– washing raw fruit and vegetables before eating (due to soil contamination)
– not using the same knives and boards for raw and cooked foods unless washed in soapy water
– cooking all foods of animal origin, including eggs
– storing food covered
– avoiding raw food after their use-by-date
– cleaning the fridge and keeping the temperature below 5 degrees, but the organism can survive and grow at low temperatures
– placing cooked food in the fridge within an hour of cooking
– when reheating food, make sure the centre is piping hot as listeria is killed by cooking food to boiling point
Foods without listeria risk include yoghurt, hard cheeses, cheese spreads and processed cheese, milk, canned and pickled foods, ready-to-eat deli meats and smoked fish heated to above 100 degrees, soft cheeses in cooked products such as pizza, hard ice-cream and gelato.
Dr Lisa Surman, CBD West Medical Centre, Perth, WA
Member of Best Practice Software’s Clinical Leadership Advisory Committee
Often patients spend time talking about current medical and social issues, taking valuable time away from dealing with what they have really come in to discuss. One of our solutions is to direct them to news articles on our website written by a doctor in our Practice that outline current issues and offer strategies to manage the problem and links to relevant, reputable websites.