Four people have been infected with Listeria in Norway after eating smoked fish from one producer.

The Norwegian Institute of Public Health (FHI) reported that three women and one man fell ill in June and were admitted to hospitals. All patients are now either healthy or improving.

They are between the ages of 50 and 80. Two live in Viken, and one each in Vestland and Oslo.

Listeria with the same genetic profile has been detected in samples from all patients, which indicates a common source of infection.

FHI, the Norwegian Food Safety Authority (Mattilsynet), the Veterinary Institute and relevant municipal officials are part of the investigation. The Norwegian Food Safety Authority has interviewed sick people and obtained samples, which the Veterinary Institute has analyzed.

Three out of four people reported having eaten either smoked salmon or smoked trout from Troll Salmon in the period before they became ill. The outbreak strain was found in two packs of smoked salmon from this company. One person had the packages in the freezer.

In July, Troll Salmon recalled smoked salmon with lot number 216 and a date of May 23.

Similar problem in 2022
The strain in this incident is also similar to the one detected in an outbreak of listeriosis in 2022 wher smoked salmon was the suspected source of infection.

From April to October 2022, the Norwegian Institute of Public Health detected listeriosis in five people. Sample dates ranged from February to October.

Cases were two women and three men aged 50 to 95 with a median of 72 years old. They lived in four counties: Nordland, Trøndelag, Viken, and Oslo, and all were hospitalized.

“The Norwegian Food Safety Authority is in close dialogue with the business, which must ensure that they do not sell products that represent a possible health hazard for consumers. The Norwegian Food Safety Authority also monitors that the company carries out necessary investigations and implements sufficient measures in production,” said Lindis Folkvord, from Mattilsynet.

At an inspection in October 2022, the Norwegian Food Safety Authority discovered the fish producer’s sampling plan was not sufficient, and that environmental samples had not been taken in line with Troll Salmon’s internal program.

The firm was ordered to take daily samples for a certain time period and to updat the sampling plan. It also carried out additional cleaning and disinfection of premises and equipment.

Listeria had been found in two smoked salmon products from the company earlier in 2022, but at a concentration below the legal limit, so they were not recalled. Samples were taken during the monitoring of ready-to-eat food in shops, a program under the Norwegian Food Safety Authority.

During the inspection, Listeria monocytogenes was found in environmental samples from the producer. However, these isolates had a different profile to the outbreak strain but were similar to those taken from the firm’s smoked salmon in the monitoring work.

In 2022, Norway had two Listeria outbreaks with 10 people sick. Infections went up from 20 in 2021 to 31 in 2022. Of these, 27 were infected in Norway and four were infected abroad. All patients were hospitalized.