Outbreaks of Salmonella and Listeria discussed at EU event

Nearly 50 people fell ill in France with Salmonella infections last year linked to chickens at a slaughterhouse. Salmonella in beef from Germany has also been documented.

Without whole genome sequencing (WGS), the low-intensity persistent epidemic could not have been detected, according to a presentation at the European Scientific Conference on Applied Epidemiology of Infectious Diseases, organized by the European Center for Prevention and disease control.

Scientists recommended strengthening surveillance through systematic sequencing of all human, food and environmental isolates of Salmonella.

In June 2020, the National Reference Center for Salmonella reported to Santé Publique France a cluster of cases of Salmonella serotype 4,5,12: i: – identified by the WGS since January 2020.

Forty-nine cases were detected, of which 46 residing in Ile-de-France. They were aged from a few months to 76 years with a median of 3 years. Among the 24 people questioned, the onset of symptoms took place from January 15 to October 18, 2020. Nine patients were hospitalized but no deaths were recorded.

Twenty-three patients said they ate chicken and eight sick people bought meat directly from a slaughterhouse. Point-of-purchase investigations for other cases have been hampered by inadequate traceability documentation of distribution channels, officials reported.

Slaughterhouse inspections identified several hygiene deficiencies in equipment maintenance and staff practices. At the end of July, the epidemic strain was isolated from samples of the chicken and the environment at the site.

The slaughterhouse was closed from late July to late September and hygiene practices were corrected. Four out of 10 sick people interviewed reported after the slaughterhouse closed that they had all eaten chicken bought before it closed and frozen after purchase. No other cases were identified after mid-October 2020.

Salmonella in beef from Germany
In another presentation, the National Reference Laboratory informed the Norwegian Institute of Public Health (FHI) of a possible outbreak in late February of this year after five cases of Salmonella Enteritidis were identified by the WGS and four of them. they were hospitalized.

In total, 30 sick people were identified, with more women than men sick, aged 2 to 91 years with a median age of 59 years. The patients lived in nine different counties. Thirteen people were hospitalized, one developed sepsis, but no deaths were reported.

Eight sick people were interviewed with a standardized questionnaire on Salmonella to assess food consumption one week before the onset of symptoms. The rest had a targeted questionnaire on ground meat and beef products. Overall, 15 of the 19 patients surveyed ate minced beef while eight ate uncooked minced meat.

After the Norwegian Veterinary Institute shared WGS data of recent isolates of Salmonella Enteritidis from meat samples, it was discovered that an isolate of a bovine carcass from Germany matched the epidemic strain. This strain has also been detected in patients from Denmark and France but investigators could not confirm the same source.

Advice to Norwegian residents has told them not to consume raw ground meat and importers have been reminded to follow the regulations. A review of the import testing guidelines for meat was also recommended.

Listeria in disgusted trout 50
A third presentation gave more details on incidents that had already been reported. It was a fatal outbreak of Listeria linked to smoked trout.

The Listeria monocytogenes epidemic has affected four countries and was detected by whole genome sequencing of clinical isolates in Germany in October 2020.

From September 2020 to August 2021, 54 patients were identified, including 33 males. The age range ranged from 0 to 93 years with a median of 79 years. Three people died. Two cases were linked to the pregnancy, including a newborn baby with sepsis and meningitis.

Forty-nine patients have been reported in Germany, two in Austria and Denmark and one in Switzerland. Sixteen of the 19 patients interviewed had eaten smoked trout.

The same type of Listeria monocytogenes that had made people sick was found in smoked trout from a brand tested in Bavaria, Germany, and in a sample from an empty packet of trout from a patient’s refrigerator in the Rhineland- Palatinate, Germany.

Investigations at the processing plant in Denmark identified Listeria monocytogenes but it was not the same type that had made people sick and the source of contamination was not found.

As smoked trout was the likely vehicle of the outbreak, it was recalled to Germany in December 2020 and Danish food authorities tightened controls at the trout processing facility. After the recall, the number of cases declined, the latest in May 2021 in Germany.

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