At least two people have died in a Listeria outbreak linked to chilled smoked trout fillets in the Netherlands.

All six sick people have been hospitalized and two died from their infections. Another person has died but no information about the cause of death was given.

Patients became ill between the beginning of February and mid-June. Their age range is 42 to 85 years old with a median of 78 years old.

Patient interviews and recall
The outbreak was reported by the National Institute for Public Health and the Environment (RIVM) and the Wageningen Food Safety Research (WFSR) institute, who jointly monitor clustering of Listeria isolates from patients and foods, when only three people were affected.

As part of listeriosis reporting, several fish consumption questions are usually asked. This information is currently available for five the outbreak patients. They all ate fish while four of them stated smoked fish and one explicitly mentioned trout.

In the third week of June, four products were recalled — smoked trout fillets from Vis Marine, Albert Heijn and two fish items from Bond Seafood. Shelf life dates ranged from June 20 to July 5.

link to single production process
An NVWA spokesman said it was not clear which of the products have caused illness and all were made by the same production process.

The NVWA was notified that three food isolates and three patient isolates formed a cluster, based on whole genome sequencing (WGS) analyses.

“Following this notification, the outbreak investigation pointed toward a single production process as the source for this outbreak. It was concluded that the safety of products produced by this process could not be guaranteed, leading to the recall,” the NVWA spokesman told Food Safety News.

“Furthermore, steps have been taken by the producer to remove possible sources of contamination. As all involved food business operators have voluntary taken all expected actions, no measures towards them were taken by the NVWA. As the recall was initiated on June 19, and given the potentially long incubation time for Listeria, we cannot exclude that more cases related to this outbreak will be identified.”

The Vis Marine 125-gram product was sold at Boon, Boni, Coop, Hoogvliet, Jan Linders, Nettorama, Plus, Poiesz, Spar and Vomar stores. Two products from Bond Seafood were sold at Jumbo Supermarkten and the AH trout fillet was available for purchase at Albert Heijn stores.