Invisible Threat: Listeria in Smoked Fish

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ish should be a regular component of our diets. It is an important source of biologically high-quality and easily digestible protein, minerals and vitamins.

ish should be a regular component of our diets. It is an important source of biologically high-quality and easily digestible protein, minerals and vitamins. However, raw, smoked and cured fish products also often contain pathogenic germs, notably listeria. People can become infected by eating contaminated food and become ill with listeriosis. In 2018, 701 cases of severe invasive listeriosis were communicated to the Robert Koch Institute (RKI), which translates into 0.8 cases per 100,000 inhabitants. Most listeriosis illnesses reported are severe and are associated with blood poisoning, meningitis or miscarriages, for example. In 2018, the disease was fatal in 5% of cases. Elderly people, people with weakened immune defences, pregnant women and their new-born babies are particularly vulnerable. Listeria can be found in a large variety of foods of plant and animal origin. Cold or hot-smoked fish are often contaminated and are, therefore, also suspected of transmitting this illness. Other fish products and seafood eaten raw, such as sushi, sashimi and oysters or cured products such as graved fish, may also be affected. "Pregnant women, elderly people or those with weakened immune defences should only eat fish and seafood that have been thoroughly heated," says BfR President Professor Dr. Dr. Andreas Hensel.

Not all Listeria bacteria cause illness. Of the 20 Listeria species described, only Listeria (L.) monocytogenes is a significant cause of infection in humans. Infections during pregnancy can lead to miscarriage, premature birth, stillbirth or the birth of a sick child. Furthermore, listeriosis mainly develops in people whose immune system is weakened by old age, pre-existing medical conditions or medication intake. They often suffer from blood poisoning, encephalitis or meningitis as well as e.g. from endocarditis or bacterial joint inflammation. Listeriosis is associated with relatively high mortality in risk groups. In healthy individuals who do not belong to one of the risk groups, an infection can lead to inflammation of the gastrointestinal tract plus a fever, with progression generally being mild.

Read more at: BFR Federal Institute for Risk Assessment