UK E. coli O157 outbreak associated with soil on vegetables

Consumers are reminded to thoroughly wash vegetables and observe good kitchen hygiene following an investigation into 250 cases of gastrointestinal illness caused by an unusual strain of E. coli O157. The investigation into the outbreak, which is now over, revealed an association between illness and handling certain loose raw vegetables in the home, which, although safe to eat, could have had soil on them containing harmful bacteria. Handling raw vegetables in the home explained many, but not all, of the cases.

Dr Bob Adak, a gastrointestinal disease expert at the HPA and head of the multi-agency Outbreak Control Team said, "Our study showed a statistically significant association with raw loose leeks and potatoes from sacks but these vegetables may not be the only source of contamination. We also want to stress that it is safe to eat these vegetables as long as they have been stored correctly, thoroughly washed before cooking and good kitchen hygiene practices are followed.
"In this outbreak, which is now over, the vegetables could have carried traces of contaminated soil. It is possible people caught the infection from cross contamination in storage, inadequate washing of loose vegetables, insufficient hand washing after handling the vegetables or by failing to thoroughly clean kitchen equipment, utensils or surfaces after preparing the vegetables."
Between December 2010 and July 2011, the Health Protection Agency (HPA), Health Protection Scotland and Public Health Wales received reports of 250 cases of infection with a particular subtype of E. coli.O157 known as Phage Type 8 (PT8) distributed across England, Scotland and Wales. The majority of these cases were mild to moderate but 74 people were assessed in hospital. Four developed Haemolytic Uraemic Syndrome (HUS) and one patient with underlying health problems died. No cases were reported in Northern Ireland and the outbreak is now over.
This outbreak was not related to the outbreaks in Germany or France earlier this year which were caused by a different strain of E. coli called O104.

Extensive investigations conducted by the multi-agency Outbreak Control Team found that people who were ill with this particular strain of E. coli O157 infection were statistically more likely to have lived in a household where leeks sold loose (i.e. not prepacked) and potatoes bought in or sold from sacks had been handled, than those who had not. There was no evidence to suggest any particular retail source or variety of the produce was responsible for people becoming ill. Illness appears to have been caused by traces of soil carrying the E. coli O157 bacteria present on the vegetables. 
Dr Andrew Wadge, Chief Scientist at the Food Standards Agency said: "It's sadly a myth that a little bit of dirt doesn't do you any harm; soil can sometimes carry harmful bacteria and, although food producers have good systems in place to clean vegetables, the risk can never be entirely eliminated. Control of infection from E. coli O157 relies on an awareness of all potential sources of the bacteria and high standards of hygiene where it may be present.
"This outbreak is a timely reminder that it is essential to wash all fruits and vegetables, including salad, before you eat them, unless they are labelled 'ready to eat', to ensure that they are clean. It is also important to wash hands thoroughly as well as clean chopping boards, knives and other utensils after preparing vegetables to prevent cross contamination."

Dr Adak from HPA, added: "It's important to remember that the risk of contracting E. coli O157 in these circumstances is very small compared with the huge benefit of eating plenty of vegetables. But E. coli O157 is a serious infection that can cause significant harm, and the public can protect themselves by taking simple but essential precautions such as preparing raw vegetables safely.
"As soon as the HPA, Health Protection Scotland and Public Health Wales saw an increase in this type of E. coli O157 we began an investigation to find the cause of the outbreak.  The multi-agency Outbreak Control Team, which included colleagues at the Food Standards Agency, worked together to find out how people were becoming infected so that action could be taken.
"Now that we have established a statistically significant association with the handling of certain loose vegetables, it warrants us sharing these findings with the public, to enable them to take the necessary steps to minimise their risk of food poisoning.
 "Eating five portions of fruit or vegetables daily is a crucial part of a healthy balanced diet, which leads to a longer and healthier life. The HPA and the other agencies involved in this outbreak investigation are committed to encouraging the uptake of five portions of fruit and vegetables a day to help people maintain a healthy weight and lower their risk of serious health problems."

Source: HPA