An outbreak of a rare type of Salmonella has been declared over in Sweden after more than 50 people fell sick. The outbreak of Salmonella Coeln is thought to have been caused by fresh sprouts.

From the end of August to October, 52 people from 14 regions were found with the same type of Salmonella Coeln thanks to whole genome sequencing. This means it is likely they were infected by a common source.

Salmonellosis cases were aged 0 to 85 years old with a median of 35. Overall, 27 females and 25 males were sick.

As there have been no new cases or samples of the outbreak strain from patients since Oct. 26, public health officials believe the outbreak has ended.

Sprouts suspected but not confirmed as source
Local infection control units and municipalities helped in the investigation with the Swedish Food Agency (Livsmedelsverket) and Public Health Agency of Sweden (Folkhälsomyndigheten).

A previous update, when the source had not been found, was given when 31 people were ill. The number of people affected by Salmonella Coeln in Sweden in 2020 and 2019 was in single figures.

The Public Health Agency of Sweden conducted a case-by-case study based on questionnaires by regional infection control units that had Salmonella patients. These people answered questions about what they had eaten during the week before illness as part of the epidemiological investigation.

Responses from outbreak patients were compared to answers from Salmonella cases that did not belong to the outbreak. This found a link between illness with the outbreak strain and consumption of sprouts. A suspected link to sprouts had also been identified during investigations in one region.

It is believed that a suspected contaminated batch was delivered to grocery stores, wholesalers and commercial kitchens at the end of August.

Sampling and analysis of remaining sprouts from ill people and from production did not find Salmonella, so suspicions that they were the source of infection could not be confirmed by microbiological analyzes.