The seven people in France part of a Listeria outbreak linked to organic dairy products fell ill over a period of 18 months, according to public health authorities.
Those infected with the same strain of Listeria were identified by the National Reference Center for Listeria, with an eighth case still under investigation.
Santé Publique France reported two people have died but the agency does not have any evidence to attribute the deaths to Listeria infection.
Details on patients
People fell ill between February 2018 and August 2019 and are aged between 36 to 93 years old. Five are women. Four live in Alsace while Burgundy, Ile-de-France, and Provence-Alpes-Côte d’Azur all have one case.
Investigations by Santé Publique France found these people had consumed organic dairy products in the weeks before contracting listeriosis. Analysis of food samples from a company, based in Bas-Rhin, Alsace confirmed contamination with Listeria. Raw milk cheeses are the suspected source of the contamination.
Testing by the National Reference Center for Listeria confirmed strains found in products had the same genetic characteristics as those isolated in the patients. Consumption of Ferme Durr products was also confirmed by several patients.
Ferme Durr recalled all dates of Durr brand organic dairy items including natural yogurt and yogurt with fruit, cream, cottage cheese, and cheese. Products were sold directly at the firm, in markets and stores throughout France. Products were also distributed in Belgium, Germany, and Luxembourg.
The action was extended a few days later to include puddings and food such as cheese and cold meats resold but not produced at the site.
All production by the company has been stopped until further notice, according to French authorities after an investigation revealed: “serious shortcomings” and results of official controls found “widespread contamination” of the facility and food products.
It can take up to 70 days after exposure to Listeria for symptoms of listeriosis to develop. Symptoms of the infection can include vomiting, nausea, persistent fever, muscle aches, severe headache, and neck stiffness.
Pregnant women, the elderly, young children, and people who have weakened immune systems are more at risk of serious illnesses, life-threatening infections, and other complications.
Certified Reference Material available
Meanwhile, the Joint Research Centre (JRC) of the European Commission has released a Certified Reference Material (CRM) to be used as quality assurance for analysis of Listeria monocytogenes in food control laboratories.
The aim is to support EU member states when monitoring listeriosis and ensure collection of comparable data on the disease.
Evaluating the subtype of Listeria monocytogenes is essential in epidemiological investigations or source tracking contamination from food factories. One of the methods used by labs for subtyping is Pulsed Field Gel Electrophoresis (PFGE). The material was certified using an interlaboratory comparison study, in which all participants used PFGE.
In the EU, 2,480 cases were reported in 2017, with a mortality rate of 14 percent. The disease is often severe with high hospitalization and mortality rates. Consumption of ready-to-eat foods such as smoked fish, deli meats and soft cheeses are the main routes of transmission.
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