According to press reports, the Danish State Serum Institute (SSI) has announced that five cases of listeriosis were recorded within a single week during April. Two of the people infected subsequently died.
Typically, only one case of Listeria infection would be expected during a seven-day period in Denmark. So the SSI considers five cases in a week very unusual. Three different strains of Listeria monocytogenes have been isolated from the five cases, one of which is very similar to a strain responsible for a large outbreak in 2014.
That outbreak began in August and affected at least 41 people, 17 of whom died. It was linked to batches of a ready-to-eat deli meat product called rullepølse, produced by a Danish company called Jørn A. Rullepølser. The company issued a nationwide recall of 30 products in response to the outbreak and subsequently ceased operations.
The source of the new cases is not confirmed, but an SSI spokesman is quoted as saying, “It’s the same bacteria as in the rullepølse outbreak. So it’s possible that the old outbreak has been rekindled.”
Read a press report on the outbreak here.