Listeria traced to fish products despite passing tests.

Track and trace four people sickened by Listeria monocytogenes linked to a fish producer in Denmark but authorities have not found high levels of the pathogen in products on the market.

The Danish Veterinary and Food Administration said intensive sampling and testing for Listeria at Hjerting Laks has not revealed any products with elevated levels. There has been no product recall because tested samples have been below the accepted limit.

DVFA report traced to Hjerting Laks as it has a DNA match between samples from the company and patients. This information was confirmed through whole genome sequencing. This gives us an excellent opportunity to find sources of outbreaks. In this case, we have a DNA match between Listeria from the patients and samples taken from the company’s production area and equipment. The specific Listeria monocytogenes ST6 sequence pattern in question is not present in other samples from other sources.

In May, FQN reported two people with the same Listeria strain, which caused 40 cases and 16 deaths last year due to consumption of contaminated deli meat.

The current outbreak involves Listeria monocytogenes ST6 and is not linked to the outbreak last year. However, one case of the five mentioned is part of the outbreak traced back to the establishment Hjerting Laks thanks to work by DVFA, Statens Serum Institut and the National Food Institute. The first person became ill at the beginning of April, the second in mid-May, the third in mid-June and the fourth at the end of June. Hjerting Laks response and past outbreak DVFA said it did not know exactly which food item caused the outbreak but suspects smoked salmon, since patients have eaten this product prior to illness.

Hjerting Laks said samples this year of final products have met all requirements; the pathogen could originate from raw materials delivered to other processors and the link to it despite the small case number. The firm previously linked with a minor outbreak of Listeria, late last year, related to smoked halibut, which declined by changing some of the production processes. No further cases related to smoked halibut were reported since November 2014. Officials said due to the incident last year DVFA has strengthened control of Listeria at the company, which co­operated throughout the process. The company change its routines about production and own check scheme. This includes upscaling their analyses program. The establishment implemented tightened supervision for the time being and until we know if the new procedures in place are effective.

Consumers should to throw away products that have exceeded the “use by” date. Also they be careful to keep the refrigerator temperature below 5ºC. Consumers should also remember that a product’s shelf life shortens after package opening. Consumers must also follow the general advices on good hygiene in the kitchen.

In Denmark about 50 cases of illness due to Listeria pathogen are registered a year. However, in 2009 and 2014 there were 90 to 100 due to major outbreaks.

Source: http://www.thelocal.dk/20150429/denmark-faces-new-listeria-outbreak