Multi-country outbreak of Salmonella Agona infections possibly linked to ready-to-eat food

Salmonella Agona, multi-country outbreak, multi-locus sequence type (MLST), Whole Genome Sequencing (WGS)
First published in EFSA Supporting Publications
26 luglio 2018
20 luglio 2018
Technical Report


A multi‐country outbreak of Salmonella Agona (S. Agona) is under investigation in the European Union (EU). Overall, 147 cases were reported by five EU countries: 122 cases since 01/01/2017, and 25 historical cases between 2014 and 2016. The United Kingdom (UK) reported most cases (129), followed by Finland (15), Denmark, Germany and Ireland (one case each). The outbreak was first detected in UK using whole genome sequencing. The close genomic relationship and the distinct seasonal spring peaks suggest that cases are part of an intermittent common source outbreak. Seventeen S. Agona food isolates from 2018, detected in UK, were found to be closely genetically related to the human strains. The contaminated food, sampled in UK, were cucumbers sampled during processing before/after washing and ready‐to‐eat (RTE) food products containing cucumbers. At present, there is insufficient epidemiological information available on the consumption of contaminated products to support the microbiological evidence provided by the isolation of the outbreak strain in food. Although the cucumbers used in all final contaminated products originated from Spain for a limited period (November/2017‐April/2018), no connection between supply chains was identified: primary producers of cucumbers were different, and cucumbers were delivered to different processing companies through different distributors in UK. All cucumber samples, taken either at primary production level in Spain or during distribution to/within UK, were Salmonella negative. The available microbiological evidence suggests RTE products containing cucumbers as a possible vehicle of infection but so far it has not been possible to identify the specific point in the production chain where the contamination occurred. Further investigations are needed to identify the source of contamination. Until the source of infection and the point of contamination along the food production chain have been identified/controlled, new cases may occur, with a high likelihood that the outbreak strains will re‐emerge in 2019.

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