Salmonella outbreak associated with imported tomatoes
5 November 2011
During the recent weeks, Statens Serum Institut has been investigating a salmonella outbreak of a rare serotype not previously detected in Denmark. The outbreak is now thought to have stopped
During the recent weeks, Statens Serum Institut has been investigating a salmonella outbreak of a rare serotype, Salmonella Strathcona. This serotype has not previously been detected in Denmark, and it has never before been recognized as the source of an outbreak.
The outbreak included a total of 40 culture confirmed cases registered in the Danish National Laboratory Surveillance System. The cases, 24 females and 16 males, comprised children and grown-ups from all over the country. The first patient became ill on 4 September, and the last on 14 October. During the same period, 14 cases in Germany and one in Austria were reported.
Small, elongated tomatoes of the type datterino have been found to be the source of the infections. The tomatoes, deriving from a producer in Southern Italy, have primarily been sold from the supermarket chain, “Rema 1000”. The tomatoes are no longer available from the Supermarket chain, and the outbreak has most likely now stopped.
Further investigations are still ongoing, including looking into if the tomatoes have been delivered to other distributers.
Tomatoes have not before been recognised as the source of salmonella outbreaks in Denmark, however, the US has seen several food borne outbreaks associated with contaminated tomatoes .
Overall, tomato-associated outbreaks are rare, and there are no recommendations not to continue eating tomatoes. It is - however - recommended always to wash and rinse fruits and vegetables thoroughly before eating them.
To detect the source of the outbreak, Statens Serum Institut carried out detailed patient interviews and collected data from electronic purchase records from “Rema 1000”. These showed that the majority of affected families had bought a specific brand of tomatoes. Based on these data a case-control study was then carried out; which found that eating small, elongated tomatoes sold in Rema 1000, was strongly associated with illness. The overall conclusion of the investigations was that the datterino tomatoes with a high probability were the source of the outbreak.
Further information:
Senior Scientist Steen Ethelberg or Senior Medical Officer Kåre Mølbak
Department of Epidemiology, phone: 0045 3268 3038