Data on foodborne norovirus has revealed almost 70 outbreaks in England in less than a decade.
The UK Health and Security Agency (UKHSA) said there is less awareness of the burden associated with foodborne norovirus outbreaks compared to those driven by person-to-person transmission.
Overall, 67 foodborne outbreaks of norovirus were reported to the UKHSA’s electronic Foodborne and non-foodborne Outbreak Surveillance System (eFOSS) in England between 2015 and 2023.
Of the 4,018 cases associated with outbreaks, 299 were laboratory confirmed but only 11 people were hospitalized. The number of cases per outbreak ranged from 3 to 1,000 with a median of 31 per outbreak.
Only three outbreaks were reported in 2020 compared to 15 in 2019. UKHSA said COVID-19 pandemic restrictions likely contributed to a drop in reported outbreaks.
There were also three outbreaks in 2015 and 2017. A dozen occurred in 2023 and 10 in both 2016 and 2018.
Food items linked to outbreaks
Only 150 cases were recorded in 2017 while 1,407 people fell sick in 2016. This year included the largest outbreak with 1,000 cases. In 2023, 487 people were ill and the largest outbreak sickened 184 people.
For the large outbreak in 2016 it was not possible to identify the food vehicle despite at least 1,000 cases being recorded. Customers and staff reported illness after eating at all 23 branches of the Wahaca restaurant group in the UK. The outbreak coincided with a new menu launch. The likely vehicle was a chipotle chili product imported from outside the European Union that was used uncooked in the implicated dishes.
A food vehicle was implicated in 39 outbreaks. The top reported categories were composite/mixed foods in 18 outbreaks and crustaceans/shellfish/mollusks in 14 outbreaks. Oysters were the most frequently implicated single food item, associated with 1,117 cases across 13 outbreaks.
In 2023, two outbreaks with 188 cases fell into the crustacean category. Another two with 81 cases were caused by fruits or vegetables and eight had unknown sources.
A total of 56 outbreaks were associated with catering settings such as restaurants/food service establishments, takeaways or fast-food outlets, accounting for more than 2,000 cases. All 12 outbreaks in 2023 occurred in catering settings.
Investigations found involvement of an infected food handler, use of an unprocessed contaminated ingredient and cross-contamination were the most frequently reported contributing factors.
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