Fish producer linked to fatal Listeria outbreak in Denmark
Almost 30 people have fallen ill and three have died in a multi-year Listeria outbreak being investigated in Denmark.
There are two different Listeria types linked to Polar Salmon Hjerting Laks from 2018 to 2024.
Findings from a recent inspection by Fødevarestyrelsen (the Danish Veterinary and Food Administration) led to the company being reported to the police.
Statens Serum Institut, the Danish Veterinary and Food Administration, and the National Food Institute investigated the incidents.
In total, 27 people have fallen sick. This includes one case each in 2018, 2020, and 2021. Two cases were recorded in 2019, six in 2022, seven in 2023, and nine in 2024.
Patients are 20 females and seven males. They range in age from 28 to 88 years old. Three people died within 30 days from the positive sample, however, it is unknown if this was from or with a Listeria infection.
International angle
One of the outbreaks was caused by Listeria monocytogenes ST1607 and 20 cases were reported from 2019 to November 2024.
In interviews with 16 sick people or their relatives about what patients might have eaten in the month leading up to their illness, 10 recalled consuming ready-to-eat fish products.
In April 2024, an outbreak assessment by the European Centre for Disease Prevention and Control (ECDC) and European Food Safety Authority (EFSA) revealed one case in Germany and two in Italy.
The outbreak strain was found in the environment of the Danish processing plant in 2023 and in products since 2021. The ECDC said this indicates the persistence of Listeria in the plant and suggests that the point of contamination had not been identified and controlled.
The other outbreak was due to Listeria monocytogenes ST8 with seven cases from 2018 to 2024.
The same Listeria type was found in environmental and product samples from the fish producer Polar Salmon Hjerting Laks. Comparison of isolates from patients and food by WGS showed they were identical.
Patients from Germany, Italy, and Sweden were also linked to these outbreaks and the same Listeria types were found in product samples exported from the Danish company.
Inspection findings
Based on an inspection at Polar Salmon Hjerting Laks in Esbjerg, the company was reported to police for not removing ready-to-eat food contaminated with Listeria from the supply chain or informing authorities.
A control report dated January 2025 reveals the company provided all analysis certificates for Listeria from January 2023 to October 2024. Testing is carried out by an external laboratory. The Danish Veterinary and Food Administration compared these analysis certificates with the certificates for the same period supplied by the external lab. There are nine Listeria-positive results that are not in the company’s digital quality management tool or in the provided analysis certificates.
The Danish Veterinary and Food Administration said the company had access to and knowledge of the analysis certificates showing Listeria detection but failed to withdraw or recall products and did not inform the agency. A part of one batch was blocked in the warehouse in 2023 after Listeria was detected. The company informed authorities that some products had been destroyed but did not say this was because of positive Listeria findings.
According to the report, the company said it would withdraw both affected lot numbers and that the issues occurred when former employees were in control.
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