Tomatoes are the probable source of a Salmonella outbreak in Sweden, according to public health officials. Folkhälsomyndigheten (Public Health Agency of Sweden) identified 71 infections from 11 counties that belonged to the outbreak. This is up from 36 illnesses in 10 counties that were linked by whole genome sequencing at the end of September. Västra Götaland, Jönköping, Halland and Dalarna reported the most patients.
Illnesses were recorded in all age groups with 46 women and 25 men ill. Of the cases so far linked to the outbreak, the last known date of illness onset was Sept. 19.
Local disease infection units, Livsmedelsverket (Swedish Food Agency) and Folkhälsomyndigheten investigated the monophasic Salmonella Typhimurium outbreak. Analysis of the Salmonella bacterial genome showed disease cases were related and it is likely they were infected by the same source.
Folkhälsomyndigheten did a case-control study to compare what those sick ate the week before they became ill with what healthy control people had eaten. Results showed that those who were ill had eaten tomatoes to a greater extent than the healthy control people.
An investigation found the tomatoes were in supermarkets at the end of August, but since they are fresh, there is no longer any stock left in grocery stores. Product testing was done but no tomatoes were positive for Salmonella.
According to foodsafetynews.com¸ the outbreak strain has multilocus variable-number tandem-repeat analysis (MLVA) pattern 3-12-11-N-211. Most people infected with Salmonella develop signs 12 to 72 hours after being exposed to the bacteria. Symptoms can include diarrhea, fever, abdominal cramps and vomiting that lasts for several days.