Tomatoes linked to multinational Salmonella Blockley outbreak involving 216 cases

An investigation published in Eurosurveillance linked a multinational Salmonella Blockley sequence type 52 outbreak to tomato consumption. Between July and October 2024, investigators identified 216 genetically related cases: 129 in the United Kingdom, 56 in France, 30 in Germany and one in the United States. Following UK case interviews, a rapid case–control study compared 29 cases with 87 controls using pre-existing control data to assess food exposures and retailers.

Multivariable Firth penalised logistic regression found an association between case status and tomato consumption combined with shopping at Retailer A (adjusted odds ratio 10.75; 95% confidence interval 1.52–103.16). Standard culture testing detected no Salmonella in 312 tomato samples. PCR detected low concentrations of Salmonella DNA in two enriched broths, but neither finding was confirmed by culture.

The combined UK epidemiological, microbiological and food-chain investigation identified tomatoes imported from Morocco as the most likely infection vehicle. The findings highlight tomatoes as a potential exposure to consider during foodborne outbreak investigations. However, the small case–control sample, wide confidence interval and absence of culture confirmation limit certainty about the association and microbiological attribution.