French control finds Yersinia in pork; cheese outbreaks reported

French officials have reported findings from a check of pork products for Yersinia and two outbreaks caused by contaminated raw milk cheese.

Yersinia enterocolitica is one of the top agents reported in Europe, with the most frequent biotype BT4 in cases of yersiniosis. Pigs are reservoirs of this pathogen, hosting it in their oral cavity and digestive tract.

The annual average number of cases in France was estimated at more than 23,600 from 2008 to 2013. Biotype BT4 with serotype O:3 is the most common in patients and is also common in pork in France.

The level of contamination by pathogenic Yersinia enterocolitica of cheeks, tongues, and other pork meats at distribution was assessed through a plan developed by the French General Directorate of Food (DGAL) in 2023. From April to December, 111 samples of cheeks, 104 tongues, and 160 fresh meats were taken at distribution in 13 regions.

Of the 375 samples, 60 were contaminated with pathogenic Yersinia enterocolitica. Tongues were more contaminated than cheeks. Only one sample of fresh meat was found to be contaminated. Of the 128 strains isolated, 125 were of the BT4 biotype.

Of the three seasons studied, the most samples and positives were taken in autumn, but the highest percentage was in spring. 

“The higher contamination on tongues and cheeks, and lower rate on meat suggests that the head deboning stage would be more at risk than the evisceration stage for contamination of pigs by pathogenic Yersinia enterocolitica,” said researchers.

Cheese outbreaks

Earlier this year, a multi-country outbreak of Yersinia enterocolitica biotype 2 with serotype O:9 infections was linked to Etoile de Provence Banon AOP raw goat’s milk cheese produced in France.

In France, Yersinia enterocolitica serotype 4 O:3 is most frequent, followed by 2 O:9. Whole genome sequencing (WGS) was implemented in 2018 for routine surveillance. In March 2024, the notification of a Yersinia enterocolitica 2/O:9 genomic cluster led to an outbreak investigation to identify the source and implement control measures.

One hundred seventy-five cases were identified in late August, with isolation dates between January and August. Patients are in all age groups, and 56 percent are women. Experts interviewed 67 sick people, and 31 confirmed consumption of unpasteurized goat’s milk cheese wrapped in chestnut leaves.

Traceback’s work led to a cheese factory. Twenty-two Yersinia enterocolitica 2/O:9 strains were detected in four different batches of cheese from the manufacturer and one strain from a boot swab at the milk producer. WGS confirmed that clinical, food, and environmental isolates belonged to the same cluster.

An Epipulse alert identified five cases in Belgium and one each in Norway and Luxembourg. Cheese was distributed in 29 countries. In July, control measures were implemented, including withdrawals from the market. The milk producer and cheese manufacturer were thoroughly cleaned. Milk was pasteurized at the producer until satisfactory analyses were obtained.

Scientists said it was the first documented outbreak of serotype 2/O:9 linked to raw goat’s milk cheese. Yersinia enterocolitica must be considered a biological risk associated with the consumption of unpasteurized milk products and included in microbiological controls at production. Udder washing is not mandatory but should be encouraged in raw milk production, and voluntary Yersinia testing should be promoted.

France is also dealing with another Yersinia outbreak linked to raw milk Mont d’Or cheeses of the brand Fruitiere Des Jarrons. According to a Rapid Alert System for Food and Feed (RASFF) notification, at least 54 people have fallen sick, and cheese was distributed to 20 countries, including Belgium, Germany, Italy, Ireland, Singapore, Switzerland, and the United Kingdom. The French publication l’Informé has put the number of people sick at 71.

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Source: https://www.foodsafetynews.com/2024/12/french-control-finds-yersinia-in-pork-cheese-outbreaks-reported/