An outbreak of Salmonella Typhimurium following an Eid al-Adha celebration barbecue in Wales (UK), July 2021

BackgroundOn a Friday evening in July 2021, Public Health Wales received notification of two cases of salmonella gastroenteritis. Both cases reported attending an Eid al-Adha celebration barbecue in a public park in Cardiff, UK two days earlier. Case finding over the weekend indicated further cases in those who had attended this event and an outbreak investigation was initiated. MethodsCases were defined as an individual with diarrhoea and/or vomiting with date of onset on the day of the barbecue, with an epidemiological link to the Eid-al Adha celebration meal. We undertook a cohort study in 36 people attending the barbecue and an associated lunchtime event, and a nested case-control study using Firth logistic regression. A communication campaign that was sensitive towards cultural practices was developed in collaboration with the community, community liaison staff and the Public Health Wales communications team. ResultsConsumption of a traditional raw liver dish, marrara, at the barbecue was the most likely vehicle for infection (Firth logistic regression, aOR: 49.99, 95%CI 1.71-1461.54, p=0.02). Meat came from two local butchers with the same supplier and food samples yielded identical whole genome sequences to those from cases. This outbreak highlights the need for appropriate food hygiene advice in communities preparing traditional dishes. ConclusionsThis outbreak identified a new vehicle of interest, a traditional raw offal dish. Future outbreak investigations, particularly where cultural events are associated with particular foods, should consider dishes beyond those on routine questionnaires to those which may be relevant to the community in question.