Large outbreak of severe Shiga toxin-producing E. coli O157:H7 infections in multiple nursing homes in Belgium, August 2025

Shiga toxin-producing Escherichia coli (STEC) O157 is a foodborne pathogen causing gastrointestinal illness. In August 2025, multiple nursing homes (NHs) in Belgium reported gastroenteritis cases among residents, which were later confirmed as STEC O157. A national outbreak investigation team was established to identify the source and implement control measures. Regional health authorities conducted field investigations, including NH visits, interviews, and exposure assessment. Microbiological and food chain investigations were coordinated nationally. We compared menus and initiated traceback investigations for high-risk food items for STEC. Using a retrospective case–control design, we calculated food-specific odds ratios and 95% confidence intervals. Additionally, we ranked exposures according to their permutation importance in a random forest prediction model. Investigations pointed to filet américain , consumed on 13 August, as the most plausible source. No leftovers were available for microbiological confirmation. We identified a batch of raw minced beef distributed to 104 institutions, including affected NHs, and found STEC-positive samples linked to it. With 71 cases and 10 deaths, this was among the largest STEC outbreaks in Belgium, prompting authorities to publish communications advising at-risk populations against the consumption of raw meat and underscoring the need to review existing recommendations on high-risk food items for foodborne infections.