- Bug causes symptoms such as vomiting and diarrhoea
- Cooking kills virus but oysters are eaten raw
By Daily Mail Reporter
Last updated at 1:55 PM on 29th November 2011
Comments (45)
More than three-quarters of British-grown oysters contain norovirus, known as the ‘winter vomiting bug’, experts have warned.
A study conducted on behalf of the Food Standards Agency found that 76 per cent of oysters tested from UK oyster growing beds had traces of the infectious bug.
Low levels of the virus, which causes symptoms such as vomiting and diarrhoea, were found in 52 per cent of the positive samples, according to the data.
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Action: The FSA and producers are finding ways to reduce norovirus levels in oysters |
However, it said the results of the study would be used as part of a review by the European Food Safety Authority, which is to advise the European Commission on what a legal safe level for norovirus in oysters should be.
Currently a safe limit for the highly infectious virus has not been established.
Although most norovirus infections are thought to spread from person to person, contaminated food is still thought to account for a proportion of cases.
A BUG THAT THRIVES IN CROWDED PLACES
- Norovirus is the most common stomach bug in the UK, affecting people of all ages.
- As there is no specific cure, it just has to run its course, but it should not last more than a couple of days.
- Those with the virus should drink plenty of fluids to avoid dehydration and practise good hygiene to help prevent it from spreading.
- The virus is easily spread by contact with an infected person, especially through their hands. It can also be caught through contaminated food or drink or by touching contaminated surfaces or objects.
- Outbreaks in busy places such as hospitals, nursing homes and schools are common because the virus can survive for several days on surfaces or objects touched by an infected person.
Eating raw oysters can carry a risk of catching the bug and other food poisoning because shellfish can contain harmful bacteria and viruses because of the way they feed.
Oysters filter large volumes of water to get their food and any bacteria and viruses that may be in the water can build up within the oyster.
Thorough cooking destroys these, but oysters are eaten raw so they may still contain viruses when eaten.
Infections linked to norovirus tend to be more common during the winter and are caught by 600,000 to one million people in the UK every year.
Andrew Wadge, chief scientist at the Food Standards Agency, said: ‘This research is the first of its kind in the UK. It will be important to help improve the knowledge of the levels of norovirus found in shellfish at production sites.
‘The results, along with data from other research, will help us work with producers to find ways to reduce the levels of norovirus in shellfish, and work within Europe to establish safe levels.’
As part of the study, scientists from the Centre for Environment, Fisheries and Aquaculture Science (Cefas) took samples from 39 oyster harvesting areas across the UK.
David Lees, the lead investigator at Cefas, said: ‘Norovirus is a recognised problem for the sector, and this study provides important baseline data to help the industry and regulators to focus on the key risks.’
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