E. coli is a common bug which is present everywhere in the environment.
Mostly it helps people to stay healthy, providing the body with many vitamins, such as vitamin K.
But some strains – such as the O157 strain – are potentially fatal.
What is E. coli O157?
Children and pensioners are especially vulnerable to E. coli 0157 which is normally found in the intestines of people and cattle and can be passed on by eating infected food and liquid.
The number of cases in the UK have tripled in the last decade, jumping from 361 cases in 1991 to over 1,000 cases in 1997.
Around 15% of cattle are now thought to carry it in their gut.
In the worst recorded E. coli outbreak, 20 people died in Scotland after attending a church lunch in Wishaw, Strathclyde.
On November 26 1996, nine days after the lunch, the first victim, Harry Shaw, 80, died. The last fatality was a pensioner who died on June 2, 1997.
Previously, the worst recorded outbreak was in Canada in 1982 when 19 pensioners from a nursing home died.
Following the Scottish outbreak, the British government set up a commission to look into the issue of food safety.
What are the symptoms?
E. coli symptoms can range from mild diarrhoea to abdominal cramps and blood in the stools.
Some patients also suffer from a complication, hemolytic uremic syndrome (HUS), which kills red blood cells and can cause kidney failure.
Children under five are particularly vulnerable to HUS. About 5 to 10% of them progress to this stage.
In severe cases, it can cause permanent kidney damage.
Young children are particularly vulnerable because they cannot tolerate much fluid and blood loss.
The elderly and people with damaged immune systems are also more at risk from the infection.
Symptoms may appear within hours or days, depending on a series of factors, including the number of organisms ingested, the person’s state of health and their natural resistance to the bug.
Most people shake off the bug within around a week with the help of antibiotics.
However, there is no evidence that antibiotics have any positive impact on the 0157 strain, and their use may increase the risk of HUS.
Anti-diarrhoeal medication should be avoided and people should take lots of fluids.
Experts advise people who notice blood in their stools or watery diarrhoea in children to contact their doctor immediately.
What can be done to prevent infection?
The Pennington Report (the commission was led by Professor Hugh Pennington) put forward 32 recommendations, all of which were accepted by the government.
Among the main points suggested by the report were:
* Lessons in food handling for children;
* Improved training for abattoir workers;
* E. coli awareness programmes for farm workers;
* Licences for butchers, requiring them to train staff in food hygiene;
* Enforced separation of raw and cooked meats in food preparation.
Experts at Britain’s Communicable Disease Surveillance Centre recommend keeping raw and cooked meat separate and ensuring that all meat is properly cooked.
Beefburgers, for example, should be cooked to a minimum internal temperature of 70°C for two minutes.
Health experts also advise that people should always wash their hands after handling raw meat and other food and not to touch manure.