Five people were infected with listeria within a one-week span earlier this month, the Danish State Serum Institute (SSI) said on Tuesday. Two of them died within 30 days of the bacteria’s discovery.

 

The institute said that two of the new cases resemble the same type of listeria that was present in batches of the popular deli meat rullepølse produced by the company Jørn A. Rullepølser last year. That outbreak began in August and infected a total of 41 individuals, 17 of whom died. 

 

Two of the other new cases resemble previous minor outbreaks while the fifth is infected with a type of listeria that has not yet been seen.

 

“It’s unusual to have five cases in one week. Normally we see one case of listeria per week. But it is also unusual that we were able to so quickly determine the type of listeria. That is a sign that our monitoring of listeria has gotten better,” SSI spokesman Kåre Mølbak said. 

 

The Jørn A. Rullepølser listeria outbreak led to a total of 30 products – including variations of rullepølse, salami and hot dogs – being recalled from stores nationwide. The company was shut down as a result. 

 

The source of the new cases was not immediately known, Mølbak said.

 

“It’s the same bacteria as in the rullepølse outbreak. So it’s possible that the old outbreak has been rekindled,” he told public broadcaster DR. 

 

SSI said that the majority of those who have been infected with listeria had weakened immune systems. Fatality rates among infected individuals is 25 percent, the institute said. 

 

Denmark normally sees around 50 listeria cases per year, but in the years 2009-2014, that number was closer to 100.