An outbreak team at the Public Health Agency of Sweden has reported on their investigation into a nationwide outbreak of Salmonella Enteritidis phage type 13a infection that is associated with imported dried vegetable spice mixes.
The outbreak affected at least 174 people from 17 of the 21 counties in Sweden between December 2014 and July 2015, but is considered to be on-going. 108 cases were found to be associated with a single restaurant in Kalmar County. Genetic typing of Salmonella Enteritidis PT 3a isolates from the outbreak revealed three different MLVA profiles, although only one was associated with cases from the implicated restaurant.
The outbreak investigation initially suspected a food with a long shelf life and likely to be eaten by a broad range of the population. Investigations at the restaurant suggested that pork tenderloin might be the vehicle, but microbiological tests identified Salmonella in an unopened pack of spice mix that was used for seasoning. The spice mix was imported from Serbia and contained vegetables including onions, carrots and parsnips.
Other unopened packs of the same brand of spice mix collected from other locations also subsequently tested positive for Salmonella Enteritidis PT 13a. Other serotypes were found in other Serbian and Croatian spice mix brands in Sweden and in Austria, suggesting that a common ingredient could be contaminated. Further spice mixes are now being analysed.
A full report of the investigation to date is published in the journal Eurosurveillance and can be found here.