Salmonella cases blamed on lettuce from takeaway outlets

A massive surge in the number of cases of food poisoning caused by a rare strain of bacteria has been linked to lettuce leaves, experts warned yesterday. More than 350 cases of food poisoning caused by the relatively uncommon strain of bacteria Salmonella Newport have been reported since September.

A massive surge in the number of cases of food poisoning caused by a rare strain of bacteria has been linked to lettuce leaves, experts warned yesterday. More than 350 cases of food poisoning caused by the relatively uncommon strain of bacteria Salmonella Newport have been reported since September.

The figure is more than twice the average annual number of cases - about 150 - according to the Health Protection Agency (HPA), which warned that the most likely source of the outbreak originated from lettuce served in fast-food, takeaway or catering premises.

All the cases reported since September have contracted an identical strain of the bacteria and have been concentrated in north-east Lincolnshire, the West Midlands, Northern Ireland and the Isle of Man. Some 33 people have been admitted to hospital and the unusually high number of cases of food poisoning caused by Salmonella Newport prompted an investigation by the HPA.

"We usually only see around 150 cases of this particular strain of salmonella each year, so when these separate outbreaks were reported to us we knew something was happening," said Dr Bob Adak, who headed the HPA investigation alongside the NHS and local authorities. "Our Salmonella Reference Laboratory carried out additional testing and has found that the strains of the bacteria are identical."

An investigation into the different foods that sufferers had eaten found lettuce was the one common factor. "In some of the local investigations the results suggest that consumption of lettuce from various catering, fast food and take-away premises are the likely main cause of the outbreaks," said Dr Adak.

"The HPA have been working closely with the Food Standards Agency to look at the supply chain of these salad products and to see if we can identify where they became contaminated. It is possible that the foods responsible for these outbreaks have now been used up; however it is important to investigate where they became contaminated, to establish whether the outbreak is ongoing, and to prevent this happening again," he said.

Salmonella Newport causes severe diarrhoea, abdominal pain, vomiting and fever. While it is spread by undercooked food or contamination from raw foods in the kitchen, a national outbreak of the strain in 2001 was also caused by lettuce.

Judith Hilton, head of microbiological safety at the Food Standards Agency, said: "Our advice is that the risk of food poisoning can be reduced by good food hygiene practices. These include thorough washing and preparing of lettuce away from other foods to avoid cross-contamination."