Focus on Listeria
What is Listeria ?
Listeria monocytogenes, more commonly known as Listeria, is a foodborne pathogen that causes a severe disease: listeriosis. It is a rare disease, but with a high mortality rate. It accounts for 25% of deaths from food poisoning*. More than 1 in 5 people who contract listeriosis die from it. Because of the seriousness of its health effects, it is essential to learn about Listeria to avoid the risk of contamination.
 France 2008-20013. Van Cauteren et al, Emerging Infectious Diseases
What are the symptoms of listeriosis?
Listeria is a single bacterium with an incubation period of 3 days to 2 months. Symptoms can therefore appear from 3 days to 2 months after ingestion. It causes mild flu-like symptoms in healthy people: fever, muscle aches and occasional gastrointestinal symptoms such as nausea or diarrhoea. The elderly and the foetuses of pregnant women are most vulnerable. The mother can infect her baby during pregnancy and cause a miscarriage or premature delivery.
How is Listeria transmitted?
Food can become contaminated with Listeria throughout the farm-to-fork process, in the production environment, during processing, or during handling and preparation in retail establishments and consumer kitchens (ILSI, 2005).
In food, the bacterium is able to multiply between 1 and 45°C and can therefore survive in the environment and multiply at refrigerator temperature (+4°C). It is also resistant to freezing, but not to cooking.
Some foods are more contaminated than others: smoked salmon and sliced sausages, pâté, meat and fish salad, raw milk and raw milk cheeses, minced meat.
How to reduce the risk of Listeria contamination?
Prevention is essential to avoid the risk of contamination, as the risk of contamination is constant. It is difficult to eliminate this contaminant completely, so the aim is to control it as effectively as possible, particularly where it may contaminate ready-to-eat and refrigerated food.
Listeria control is based on the detection and management of risk areas. The daily use of enzyme solutions allows a thorough cleaning of work surfaces, floors and traps.
Special attention should also be paid to damaged equipment, cracks, crevices and hollows. And don’t forget to keep an eye on the occasional cleaning areas: walls, refrigerators and freezers.
Listeria is destroyed by the usual processes of pasteurisation and cooking of food. However, contamination can occur after the cooking process. For example, through contact with unpasteurised food or equipment (refrigerator) or materials that have not been disinfected, or a lack of hygiene by staff.