Three hundred and one people were surveyed, and 215 individuals (71.4%) reported vomiting and/or diarrhoea following consumption of a donut purchased from the business over a five-day period.
All ill respondents reported eating a donut. The medians of incubation period and illness duration were 34 hours (interquartile range, IQR: 29–42 hours) and 48 hours (IQR: 29–72 hours) respectively. Diarrhoea, vomiting and abdominal pain were the most commonly reported symptoms.
Eight out of 11 specimens collected from ill individuals were positive for norovirus. For the case-control study, data from 59 attendees were collected, with an attack rate of 46% (27/59). Eating any kind of filled donut was associated with a person becoming ill (odds ratio: 10.4; 95% confidence interval: 1.18–478.13).
No single flavour was identified as the likely source of infection.
Elevated levels of coliforms were present in two samples of donut filling obtained during the food safety inspection.
Donuts are a novel vehicle for norovirus infection. This implicated pathogen, plus evidence collected at the food premises suggestive of faecal contamination, indicates the source of this outbreak was likely an ill food handler. The findings of this outbreak highlight the importance of excluding food