Public Health England (PHE) and the Food Standards Agency (FSA) are continuing to investigate an outbreak of E. coli O157, which has been linked with eating mixed salad leaves.

PHE has confirmed that 151 cases of this strain of E. coli have been identified (figure correct as at 13 July 2016). This is 144 in England, six in Wales and one in Scotland, with the South West of England particularly affected. 62 of the cases are known to have received hospital care and, sadly, two of the individuals with E. coli O157 infection have died.

Dr Isabel Oliver, director of PHEs field epidemiology service, says, "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. WGS technologies 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 FSA 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 its important to be aware that wher 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."

The FSA is reminding people of the importance of good hand and food hygiene practices. All vegetables, including salads, intended to be eaten raw should be thoroughly washed unless they are specifically labelled ready to eat.