Yersinia outbreak linked to imported iceberg lettuce

An outbreak of Yersinia in Sweden has ended with iceberg lettuce because the suspected supply of an infection.

From January till the start of February this yr, twice as many individuals fell in poor health with Yersinia an infection as did throughout the identical interval in a standard yr.

From 53 instances of Yersinia enterocolitica, 33 lived in Stockholm, Västra Götaland and Halland. Isolates from 24 of those instances have been typed by complete genome sequencing and 16 outbreak sufferers with clustered isolates of sequence sort 18 may very well be recognized.

Of those 16, eleven have been ladies and 5 have been males aged 7 to 34 years previous. All fell in poor health between Jan. 4 and 18.

Managing assets
Rikard Dryselius, a microbiologist at Folkhälsomyndigheten (Public Well being Company of Sweden), mentioned assortment and typing of Yersinia isolates isn’t finished routinely within the nation.

“As an alternative, particular person counties can ask for assist with typing Yersinia once they see a necessity. Alternatively, we might ask the laboratories to ship in isolates if we see a rise in instances nationally that ought to be investigated,” he mentioned.

“As a result of strained state of affairs for an infection management models and scientific laboratories throughout the pandemic, we selected to request interviews/questionnaire responses and assortment of isolates solely from the counties the place the rise was highest. It’s due to this fact very seemingly that there have been greater than 16 outbreak instances however the lack of extra isolates to sequence signifies that we can not affirm this.”

Folkhälsomyndigheten, an infection management models within the Stockholm, Västra Götaland and Halland areas and Livsmedelsverket (Swedish Meals Company) investigated the incident.

Well being officers interviewed sick folks and compiled questionnaire responses about what and the place they ate earlier than sickness onset.

A case-case research the place questionnaire responses from outbreak instances have been in contrast with solutions from folks with Yersinia an infection that didn’t belong to the outbreak was finished.

Restaurant and iceberg lettuce hyperlink
The investigators discovered the outbreak instances had, to a higher extent, visited a sure restaurant chain. Comply with-up interviews about what that they had eaten led to iceberg lettuce being suspected because the supply of an infection.

Based on the trawling questionnaire despatched to outbreak instances, seven out of 12 talked about that they had visited the restaurant chain earlier than falling in poor health whereas seven out of 72 instances with yersiniosis who responded to the identical questionnaire in 2019 talked about that that they had finished so.

The suspicion of a contaminated batch of iceberg lettuce distributed to a restaurant chain was strengthened by the outbreak timeline, which urged {that a} product with a large geographical unfold and a restricted shelf life was the underlying trigger.

Sweden has no important manufacturing of iceberg lettuce right now of yr and makes an attempt are being made to hint the nation of origin.

In the meantime, investigations are ongoing to search out the supply of a Salmonella Enteritidis outbreak within the nation. It isn’t associated to the Salmonella outbreak in Norway linked to meat from Germany.

The primary individual fell in poor health on the finish of December 2020. There are 25 confirmed sufferers throughout 14 areas in southern and central Sweden.

Virtually three quarters of sufferers are youngsters youthful than 10 years of age and 4 are older than 70.

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