Escherichia coli (E. coli) outbreak in United Kingdom

A significant increase in the number of cases of E. coli, specifically E. coli O157 infection, was observed in the United Kingdom in late June, and the incident was declared and managed as a national outbreak. The outbreak was reported to WHO on 1 July 2016.

As of 14 July, 158 cases had been identified: 105 were classified as confirmed and 53 as probable. Four of these patients remain in hospital. Two people have died, with E. coli infection listed as a causative factor in both cases.

Multiple analytical studies have provided evidence that the consumption of mixed salad leaves, particularly from catering establishments such as cafes and restaurants, is associated with the infection. Sampling and microbiological examination of salad products is continuing, although all results to date have been negative for the strain of E. coli causing the outbreak. This strain is not related to strains currently circulating among livestock in the country, but is closely related to sequences identified in people reporting recent travel to the Mediterranean region. This suggests that the outbreak strain is likely to be imported. Nevertheless, other European countries have not reported similar increases, and the strain has not been reported outside the United Kingdom.

E. coli is a bacterium that is commonly found in the gut of humans and warm-blooded animals. Most strains are harmless, but some can cause severe foodborne disease.

Public health response

In response to the outbreak, a small number of wholesalers have stopped adding some imported leaves to their mixed salad products, pending further investigations.

Public Health England (PHE) is working with the European Centre for Disease Prevention and Control (ECDC), the Food Standards Agency of the United Kingdom and the European Commission to identify the source of the outbreak. PHE is also providing advice to the public and keeping it informed about the continuing investigations. WHO continues to monitor the epidemiological situation and conduct risk assessment based on the latest available information. 

Further details about the outbreak are now available in a recent issue of Disease Outbreak News published by WHO headquarters.