Outbreak ofSalmonellaThompson Infections Linked to Imported Rucola Lettuce

Abstract

On November 15, 2004, a cluster of three cases of Salmonella Thompson infection was registered by the Norwegian reference laboratory. In the following days further cases occurred, prompting a case-control study among the first 13 cases and 26 matched controls. By December 31, 21 cases had been reported, with the first onset on October 24. Consumption of rucola lettuce (Eruca sativa, also known as rocket salad or arugula) (OR 8,8 [1,2-infinity]) and mixed salad (OR 5,0 [1,0-infinity]) was associated with illness. On November 26, Swedish authorities notified the finding of Salmonella Thompson in rucola lettuce through the EU Rapid Alert System for Food and Feed. Later, several countries reported finding this and other Salmonella serovars and Campylobacter in rucola produced in Italy. In response to our alert through the international Enter-net surveillance network, Sweden and England also reported an increase of cases. Salmonella Thompson isolates from products and patients from several countries showed high similarity by pulsed-field gel electrophoresis, but some isolates showed significant differences. We think that the outbreak in Norway reflected a larger international outbreak caused by rucola imported from one Italian producer. Findings of other pathogens indicate a massive contamination, possibly caused by irrigation with nonpotable water. Rapid international information exchange is invaluable when investigating outbreaks caused by internationally marketed products.

Salmonella Thompson outbreak associated with consumption of chicken shawarma and the usefulness of genome sequencing in the investigation

“…Details of outbreaks associated with S. Thompson have been published previously (1)(2)(3)(4). One outbreak which occurred in 2012 involved 1,149 confirmed cases in the Netherlands, which was attributed to the consumption of smoked salmon (1).…”

Survival of Enteric Pathogens During Butterhead Lettuce Growth: Crop Stage, Leaf Age, and Irrigation

“…Leafy vegetables, such as lettuce, are considered by the U.S. Food and Drug Administration as high-risk food (Klein et al, 2009). In Europe as well, various E. coli O157 (Welinder-Olsson et al, 2004;Friesema et al, 2008;Sö derströ m et al, 2008) and Salmonella outbreaks (Ward et al, 2002;Horby et al, 2003;Nygå rd et al, 2008) have been related to the consumption of lettuce.…”

Interaction of Salmonella enterica with basil and other salad leaves

“…The newsworthy international outbreaks of S. enterica that have been linked to ready-to-eat plant produce include a Scandinavian/UK outbreak of S. enterica serovar Thompson associated with consumption of rucola lettuce (Nygård et al, 2008), a Danish outbreak of S. enterica serovar Anatum infection linked to imported basil (Pakalniskiene et al, 2006), a tomato-associated outbreak of S. enterica serovar Braenderup infection in the United States (Gupta et al, 2007), an outbreak of S. enterica serovar Typhimurium (S. Typhimurium) DT204b in several European countries associated with the consumption of lettuce (Crook et al, 2003) and an outbreak of S. enterica serovar Senftenberg (S. Senftenberg) infection associated with imported Israeli basil affecting the United Kingdom, Denmark, the Netherlands and the United States (Pezzoli et al, 2007).…”