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Smoked Fish and Low Levels of Listeria

UK - The food poisoning bug listeria is rarely found above legal limits in smoked fish on sale in UK shops, according to a new survey published by the Food Standards Agency today.

The study, which ran between July and November 2006, looked at the levels of listeria in ready-to-eat smoked fish in over 1,000 supermarkets, fishmongers and grocers across the UK. More than 3,000 samples were analysed to check for Listeria monocytogenes, the main type of listeria that causes illness in humans. While traces of Listeria monocytogenes were found in 302 samples, 99% were within the legal limit for ready-to-eat foods. Only three samples in the whole survey breached legal limits.

Dr Andrew Wadge, Chief Scientist at the Food Standards Agency said: 'Although only a snapshot of one type of food, this survey adds another piece to the listeria puzzle. We know cases are on the increase in the over-60s, but we don't know why. These findings suggest that, listeria isn't generally a problem in ready-to-eat smoked fish at point of sale – but it doesn't tell us what happens when people get it home. Are they preparing and storing food correctly and eating it within its 'use by' date? These and other questions are at the heart of further work we’re doing with our expert scientific committees to get to the bottom of this increase in listeria.'

Since 2000, the reported number of illnesses from listeria in the UK has doubled, particularly in people over 60 years of age. In 2005, there were an estimated 400 cases, of which 380 people were hospitalised and 130 people died, making listeria the biggest cause of death from food poisoning. Listeria is found naturally in the environment and can be present in a wide range of foods, from pâtés and soft cheeses to cooked sliced meats and smoked fish.

To help minimise the risk of listeria, the Agency has recently published guidance for those preparing and supplying chilled ready-to-eat foods. For more information about listeria and the Agency's work in this area can be found at the links below.

The science behind the story

Although listeria isn't common and rarely affects healthy people, it can cause serious illness in vulnerable groups, such as people with reduced immunity, particularly those over the age of 60 and pregnant women. People with weakened immunity could include those who've had transplants, are taking drugs that weaken their immune system, or who have cancer that affects their immune system, such as leukaemia or lymphoma. Among these vulnerable people, the illness is severe and can be life-threatening.

To help prevent illness from listeria, special care should be taken to follow the storage instructions on food labels. Chilled foods should be kept in the fridge and put back as quickly as possible after use, and food shouldn't be used after its 'use by' date. Vulnerable groups, such as people over 60 with weakened immunity and pregnant women, should avoid eating soft ripened cheeses such as Camembert and Brie, soft blue cheeses and pâtés, including vegetable types.

Ellen Hardy

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