A German risk assessment agency has advised vulnerable people only to eat fish and seafood that has been thoroughly cooked because of the risk of listeriosis.

The German Federal Institute for Risk Assessment (BfR) told people with an increased risk of developing listeriosis that they do not need to avoid it but should only eat fish or seafood that has been properly prepared. The German Nutrition Society recommends at least one fish meal every week. Fish is an important source of protein, minerals and vitamins, according to the society.

However, elderly people, those with weakened immune defenses, pregnant women and their new-born babies are particularly vulnerable to Listeria infection. Such risk groups should not eat raw, smoked or cured fish or seafood products.

Listeria can be killed by heating food to a core temperature of 70 degrees C (158 degrees F) for at least two minutes. In 2018, 701 cases of severe invasive listeriosis were reported to the Robert Koch Institute (RKI).

Listeria contamination of fish
Raw, smoked or cured fish products and seafood such as sushi, sashimi, oysters, cold or hot smoked fish like smoked salmon and cured fish such as graved salmon are frequently contaminated with Listeria, according to the BfR.

A total of 7 to 18 percent of the samples of cold-smoked or cured fish products examined by food authorities in Germany between 2007 and 2017, and 3 to 9 percent of hot-smoked fish products contained Listeria monocytogenes.

Even low concentrations are hazardous to risk groups, for example when products are stored above temperatures recommended by the manufacturer or when they are eaten after the best-before date. Handling contaminated products risks transferring Listeria to other foods, according to the BfR.

Meanwhile, the BfR is involved in a project to improve analytical methodologies to identify and quantify allergens from insects that are relevant for food production.

Developed methods in the Allergen-Pro project will be used by partners in routine analysis and proposed for enforcement purposes by official control laboratories. The research, which runs until August 2023, will deliver information about the clinical relevance of insects as a potential allergic food product.