What is Listeria?
The recent outbreak of listeriosis in Denmark, which has also received a lot of media attention in the rest of Europe, has brought attention to the bacteria Listeria monocytogenes, which is found in nature all around us, but normally not in dangerous levels.
Listeriosis is the name of the illness caused by Listeria monocytogenes. It is most commonly contracted through ingestion of contaminated food items, most often cheeses made from unpasteurized milk and ready-to-eat products of meat or seafood including cold-smoked fish. The current outbreak has shown that Listeria can also be present in cooked products where the bacteria have been introduced after the heat-treatment, for example during the slicing or packaging process.
Symptoms
The illness most commonly shows itself as flu-like symptoms such as fever and muscle aches, often preceded by diarrhea or other gastrointestinal symptoms. At risk are the elderly, newborns and people with an already weakened immune system. The infection is usually not a problem to otherwise healthy persons, who will usually only develop a non-invasive illness. Listeriosis is treated with antibiotics, but has a high mortality rate of about 20%.
Route of infection
Listeria can be found everywhere in our surroundings and most people eat contaminated foods from time to time, but only a few contract listeriosis. In many cases the content of listeria will be too low to cause an infection. However, the bacteria can survive the absence of oxygen and can grow at refrigerator temperature, but is killed when heated to 72°C or more for at least 15 seconds. This makes it a risk in foods that have not been heat treated at high temperatures such as cheeses or cold smoked meats and fish. As listeria is not a spoilage bacterium and is invisible as well as odorless, it is impossible to detect without laboratory analysis.
Prevention
It is not possible to eliminate listeria completely, as it is naturally occurring in our surroundings, for example in soil and waste water. There are possible measures that consumers can take to avoid getting ill from it, such as ensuring good hygiene in their own kitchens, adhering to best-before-dates and making sure that their refrigerators are set at the correct temperature. Food producers have the responsibility to keep the amount of listeria at an absolute minimum. The most important risk factors for food producers are control of their raw material supply and hygiene/cleaning in the production area – read more here.
Royal Greenland's smokehouse is run according to strict HACCP procedures for handling and hygiene in order to eliminate contamination risks. At the same time, samples from each batch are examined by the local quality department, as well as occasionally by the corporate quality department. External audits are carried out by the IFS and Danish Veterinary and Food Administration, who released this statement, concluding that products from the Royal Greenland smokehouse will never have listeria amounts above the dangerous levels during the shelf life of the product.
Moreover, research conducted by the Technical University of Denmark (DTU) in cooperation with Royal Greenland shows that the addition of certain organic acids can prevent listeria from growing during the shelf life of a product. Read more here A procedure that last year prompted the Danish Ministry of Food, Agriculture and Fisheries to issue a statement warranting that the level of listeria in Royal Greenland smoked and marinated products will not exceed 100 colony forming units per gram during the shelf lives of the products.
