Raw oysters have been held officially responsible for the outbreak of the norovirus that allegedly poisoned over 500 people at Heston Blumenthal’s The Fat Duck restaurant last February.
The Health Protection Agency’s (HPA) investigation into the cause of the outbreak, which saw Blumenthal close his restaurant for three weeks, found that 15 per cent of The Fat Duck’s diners during January and February reported symptoms of diarrhoea and vomiting.
Inadequately handled or cooked razor clams, raw oysters, and shellfish contaminated from source have all been partly to blame for the outbreak, with reports of illness from other establishments using oysters from the same source.
While Blumenthal cooperated fully with the HPA’s investigation, the agency highlighted that ‘weaknesses in procedures’ at the restaurant may have contributed to the outbreak, which saw a delayed response to the incident and staff continuing to work when they should have been off sick.
Dr Graham Bickler, HPA South East regional director, said: “Individuals infected with norovirus can readily transfer the virus onto foods they prepare. The virus will remain viable and capable of causing illness in those foods that are not subsequently cooked…the more intensively that food is handled the more likely it is to become contaminated by infected food handlers.
“This investigation has been long, complex and thorough. It confirms the well-known risks that raw shellfish pose. Oysters and other shellfish can become contaminated with norovirus originating from human sewage, especially during winter months.”
A spokesperson for The Fat Duck said the outbreak had nothing to do with hygiene or food preparation at the restaurant.
"The restaurant employs strict food preparation processes and follows all recommended guidelines," she said. "There is absolutely no evidence that the virus was passed on through preparation and handling of food at the restaurant by any staff. The restaurant has a clear policy on sickness and returning to work, including following the 48hours guidance as noted in the HPA¹s own Norovirus Fact Sheet.
"The restaurant had absolutely no knowledge of any staff returning to work whilst ill or infectious."
Blumenthal reopened The Fat Duck in March after following advice from the HPA, but was thought to have lost more than £100k in lost bookings.
The HPA has now advised restaurants to be scrupulous when it comes to handling shellfish in particular, in order to prevent the spread of food poisoning.