On 14 July Public Health England (PHE) is continuing to investigate an outbreak of E. coli O157, which appears to be associated with eating mixed salad leaves.

Following the last update on 5 July, PHE can now confirm that 151 cases of this strain of E. coli have been identified (figure correct as at 13 July 2016). This is 144 in England, 6 in Wales and 1 in Scotland, with the South West of England particularly affected. 62 of the cases are known to have received hospital care and sadly, 2 of the individuals with E.coli O157 infection have died.

Dr Isabel Oliver, director of PHE’s field epidemiology service, said:

PHE has been working to establish the cause of the outbreak and has identified that several of the affected individuals ate mixed salad leaves including rocket leaves prior to becoming unwell. Currently, the source of the outbreak is not confirmed and remains under investigation; we are not ruling out other food items as a potential source.

PHE is using various approaches including whole genome sequencing (WGS) technologies to test samples from those affected. WGStechnologies are at the forefront of improving the diagnosis of infectious diseases and this testing has indicated that the strain involved is likely to be an imported strain, possibly from the Mediterranean area.

PHE is also working closely with the Food Standards Agency to trace, sample and test salad products grown in the UK and other parts of Europe. All food sample results to date have been negative for E.coli O157, but it’s important to be aware that where food has been contaminated with E.coli O157, it is not always possible to identify the bacteria on food testing.

As an additional precautionary measure, we have advised a small number of wholesalers to cease adding some imported rocket leaves to their mixed salad products pending further investigations.