In February 2022, a small five-single nucleotide polymorphism (SNP) single linkage cluster of eight cases of infection with monophasic Salmonella enterica subsp. enterica serotype Typhimurium (1,4,5,12:i:-) eBG 1, sequence type (ST) 34 was identified in the United Kingdom (UK). The cluster was unusual, with all but one reported case younger than 10 years, and the strain demonstrated genotypic markers of an unusual antimicrobial resistance pattern not commonly seen in livestock, food or human disease cases in the UK. The cluster was not closely related to any other UK strains of monophasic S. Typhimurium.
Exploratory interviews using an open-ended, anthropological approach (not binary yes/no questions) were undertaken with the parents/guardians of five cases in England for hypothesis generation. Subsequently, a targeted questionnaire to refine hypotheses identified through the exploratory interviews was used, confirming a strong signal for a specific brand of chocolate products.
Following the UK’s notification on the European Centre for Disease Prevention and Control (ECDC) EpiPulse Food and Waterborne Diseases (FWD) platform on 17 February 2022, and an Early Warning and Response System (EWRS) alert on 25 March, Germany, Sweden, France, the Netherlands and subsequently Luxembourg, Norway, Ireland, Belgium and Spain reported confirmed or probable cases in their respective countries.
a Case onset date (n=108) is not consistently available for all reported cases, therefore date of sampling has been used where case onset date is unavailable (n=39) or date of receipt at reference laboratory where both onset and sampling dates are unknown (n=3).
b Probable cases were reported by Belgium (n=19) and Germany (n=2) (data as of 13 April).
EEA: European Economic Area; EU: European Union; UK: United Kingdom.
Multi-country collaboration through teleconferences and sharing of information between public health agencies and reference laboratories indicated that cases in affected countries commonly reported consumption of a specific brand of chocolate products. Overall, of 101 case interviews carried out across the 10 affected countries, 88 cases (87%) confirmed consumption of these products. The most commonly consumed product was Product A, marketed primarily for children in the age group 3–10 years, but multiple other product types were also reported.