Feta safe than sorry - gastroenteritis outbreak associated with contaminated cheese

Abstract A gastroenteritis outbreak among attendees at a catered HSE event was notified. No faecal samples were obtained - all cases had recovered. An outbreak control team was convened. A retrospective cohort study hypothesised that “people who attended the HSE event and subsequently became unwell did so as a result of consuming food at the event”. Epidemiological, environmental, and microbiological investigations commenced. An outbreak-specific food questionnaire was distributed. The food business was inspected, obtaining food samples. Survey responses were analysed.The attack rate was 25%. Associations were identified between illness and specific foods. Multivariable regression highlighted: feta salad (OR = 36.22 [95% CI 2.24-585.52] p = 0.01), and turkey (OR = 12.57 [95% CI 1.12-140.58] p = 0.04). Most (93%) turkey consumers had consumed feta salad. Microbiology of unopened feta cheese, sourced by the caterer from a supermarket, was positive for E coli at 1.7 x 105. The Food Safety Authority of Ireland corroborated separate illness complaints from a family consuming the product. The supermarket voluntarily withdrew the product internationally.This outbreak prompted a cross-sectoral food safety investigation. Despite no pathogen detection in a faecal samples, epidemiological evidence led to the withdrawal of contaminated feta by the supermarket, removing over 1000 units from the market, emphasising the importance of epidemiology in protecting public health. Key messages • Epidemiological investigation resulted in mass contaminated cheese withdrawal internationally. • Cross-sectoral work is important to safeguard public health.