Four people have died and 12 people have fallen ill following a Listeria outbreak linked to salmon. Listeria, also known as Listeria monocytogenes, is a life-threatening airborne bacteria spread through food or contact with farm animals. The European Centre for Disease Prevention and Control (ECDC) said it was “likely” the extent of the outbreak has been underestimated.
As the outbreak was identified through sequencing and only a few EU countries use this technique to identify Listeria, not all cases may have been identified so far and further outbreaks could continue.
The Listeriosis cases recorded are in Denmark, Germany and France.
The first case was identified in October 2015 in Denmark and the most recent in May 2018 in Germany.
Five of the people contracted the disease between May and August 2017 and one died within 30 days of diagnosis.
A historical confirmed case had disease onset of October 2015.
ECDC said ready-to-eat salmon products, such as cold-smoked and marinated salmon are likely to be the source of the outbreak of Listeria.
The deaths matched the outbreak strain identified by whole genome sequencing.
In August 2017, Denmark identified the first cluster of cases linked to ready-to-eat cold-smoked salmon processed in Poland by BK Salmon.
However, because of a lack of data on Listeria monocytogenes, the ECDC said it was not possible to confirm the contamination came from the Polish processing company.
Even though control measures were put in place following the Danish outbreak, the same strain was found in a salmon product in France in October 2017 and in a patient in Germany in May 2018.
This means the source of contamination could still be active and spreading to other EU countries, so further outbreaks could strike.
A EU-wide study coordinated by ECDC revealed more than half of the severe listeriosis cases in the European Union belong to clusters.
Many of the cases are not being picked up fast enough by the current surveillance system.
What is Listeria?
Listeria monocytogenes is a food borne disease-causing bacteria which can cause the rare infection Listeriosis.
The disease is usually caught from eating food containing listeria bacteria.
The number of reported cases has been increasing since 2008 and in 2016, 536 cases were reported, including 247 deaths, the ECDC reports.
Pregnant women, the elderly, newborns and people with weak immune systems are at higher risk of contracting listeriosis.