An outbreak of Shiga toxin-producing Escherichia coli serotype O26:H11 associated with dried fruit, UK 2023

Abstract

Shiga toxin-producing Escherichia coli (STEC) are zoonotic, foodborne pathogens that can cause large outbreaks of infectious gastrointestinal disease, including haemolytic uraemic syndrome (HUS) which can be fatal. This report describes an investigation into a foodborne outbreak of STEC serotype O26:H11 stx2a/eae, involving 40 confirmed and probable cases (confirmed cases: 54% female and 76% aged 0-9 years old), including 19 children with HUS. Whole genome sequencing (WGS) analysis detected the outbreak and revealed the outbreak strain was multidrug resistant and likely originated from outside the United Kingdom. Epidemiological analysis showed greatest odds of exposure among cases for consumption of a dried fruit product, predominantly in multi-packs. Batch numbers of the packs consumed by cases were rarely available, and where recorded, other packs in the same the batch were unavailable for testing; therefore, targeted microbiological testing was not possible. Fruit for drying can become contaminated when the crop is exposed to irrigation water or rainwater run off containing animal faeces. For STEC, where detection of the causative agent in food is challenging, we recommend establishing multi-source weight of evidence frameworks that promote the application of epidemiological and food chain evidence for public health action, and the expansion of global surveillance networks to enhance the detection of foodborne threats at home and abroad.