Matís microbiology laboratories, both in Reykjavík and Neskaupstaður, have been analysing a wide variety of samples for Listeria bacteria. Listeria monocytogenes is the primary causative agent Listeria of the family and causes a disease known as "Listeriosis". Symptoms can range in severity from flu-like symptoms to meningitis in infants, septicaemia and even miscarriage in pregnant individuals. In recent years, two to five cases have been diagnosed in Iceland annually, but in 2024 more cases were recorded, seven in total.
Listeria bacteria are found widely in nature, both in the general environment (e.g. in soil and plants) and in the intestines of humans and animals. Listeria the prevalence is so widespread that contamination of processed foods is almost unavoidable. For this reason, pregnant individuals and others in high-risk groups are generally advised to avoid dishes such as smoked and cured salmon, sushi/sashimi containing raw fish, pâté, certain types of cheese — including brie and camembert — and deli meats such as ham, where Listeria species have repeatedly been found over the years.
Since the founding of Matís, we have analysed over 13,000 samples for Listeria. The samples are most commonly food products, but so-called swab samples can also be analysed to determine whether Listeria is present on surfaces or in food production equipment. Such analyses can assist food producers in assessing whether cleaning practices are sufficiently thorough, as Listeria tends to hide in hard-to-reach areas and can grow at very diverse conditions.
Matís operates as National Reference Laboratory (National Reference Laboratory) of Iceland with regard to Listeria monocytogenes. The statutory role and main duties of reference laboratories are varied, including participation in the development and validation of analytical methods, and providing scientific and technical assistance to competent authorities.
A recent report from ANSES, the European Union Reference Laboratory (EURL) for Listeria monocytogenes entitled: "Bibliographical review on Timing for Surface Sampling in Food Processing Environments to Detect Listeria monocytogenes“ underlines that constant vigilance is required with regard to L. monocytogenes in food production, and that it may be necessary to update guidelines on the optimal sampling points in the food production process in order to increase the likelihood of reliable results.
On the website of the Icelandic Food and Veterinary Authority (MAST), information can be found on information about Listeria and general recommendations to reduce the risk of contamination.
