German Listeria outbreak linked to fish from Poland

German officials appear to have solved a multi-year Listeria outbreak.

Robert Koch Institute (RKI) scientists assigned 11 notified listeriosis patients to the incident. Despite the risk of Listeria from smoked or graved salmon being known for some time, data shows contamination still exists in production facilities and outbreaks are ongoing with further cases expected, said scientists.

Five people fell ill in 2019, one in 2021, three in 2022 and two in 2023. Five men and six women were affected, aged between 69 and 91 with a median of 79 years old.

One person who was positive for Listeria infection was reported as deceased because of causes other than listeriosis.

A Rapid Alert System for Food and Feed (RASFF) alert identified Listeria monocytogenes in smoked salmon from Poland.

“A RASFF-notification was issued because of an official sample of the mentioned product originating from Poland. Listeria monocytogenes was isolated from that sample. The link to the cluster of human cases was made by whole genome sequencing and comparison to the sequences from isolates of human origin,” said a spokesman for the Federal Office of Consumer Protection and Food Safety (BVL).

Broader problem
The specific sequence cluster type that caused the outbreak was mentioned in RKI’s epidemiological bulletin earlier this year when nine cases were known about.

This was part of wider work that identified 24 outbreaks of listeriosis across federal states with links to smoked or graved salmon products as the cause since 2010.

RKI and the Federal Institute for Risk Assessment (BfR) said measures taken so far don’t seem to be enough to protect consumers.

“The fact that cases continue to occur for many outbreaks, although possible fish products and manufacturers have been identified, casts doubt on the efficiency of measures taken and strategies pursued to minimize Listeria contamination,” they added.

People at an increased risk of listeriosis should only eat fish and seafood that have been well cooked. Smoked and graved salmon products should not be offered to vulnerable groups, such as immunocompromised people and the elderly in healthcare facilities, said the BfR.

(To sign up for a free subscription to Food Safety News, click here.)