Following on from our recent Norovirus: prevention and control blog. We wanted to highlight the risk associated to shellfish and particularly oysters.

If you were not already aware, norovirus can also be contracted by eating contaminated food – in particular, shellfish.

Shellfish, such as oysters, are a key source of the norovirus infection as they can accumulate and concentrate virus particles. Oysters contaminated with norovirus pose a particular risk to human health as they are often consumed raw.

Peter Christopher-Ohrt, Managing Director Technical Services, Food Alert Ltd, comments: “A large proportion of our clients serve oysters and shellfish and we work closely with them to minimise the risk of a norovirus outbreak within their restaurants.”

“Oysters are traditionally grown and harvested in estuaries which, during the winter months, are more likely to become contaminated by noroviruses, due to the difficulty of removing the viruses from treated sewerage which is discharged into the estuary. To reduce the risk, all oysters must be depurated (cleaned) for a minimum of 42 hours in clean water.”

“As the virus is particularly prevalent between November and March it is recommended that high risk consumers, such as infants, the elderly and those with a low immune system, avoid eating oysters as they are more susceptible to infection.”

“At Food Alert, we offer specific advice and support to our clients to help minimise the risk of a norovirus outbreak from shellfish. We focus on incorporating safe working practices into every day practice and providing systems in their food safety management systems, which increases their due diligence defence.”

For further information and expert advice on managing your food hygiene standards, then please contact us on 020 7244 1900 or via email at




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