UK lettuce in pre-packed sandwiches was likely cause of fatal E.coli outbreak

UK grown lettuce in pre-packaged sandwiches was the likely cause of the UK's largest ever STEC 0145 E.

coli outbreak, a new report concludes. However, despite extensive investigations, authorities are unable to confirm how the lettuces, thought to be behind the fatal outbreak, became contaminated.

Between May and November last year, 293 people were affected by the bacteria - which can cause severe food poisoning - with symptoms including diarrhoea, stomach cramps, vomiting and fever. Two people died.

Almost half of those affected were admitted to hospital with 11 people developing complications such as Haemolytic Uraemic Syndrome (a condition which causes kidney failure). The rapid rise in STEC 0145 - a Shiga toxin-producing Escherichia coli - cases, that was detected through routine disease surveillance, led to a multi-agency investigation across all four UK nations.

The food history of those affected and subsequent scientific studies allowed UK agencies to identify three common sandwich manufacturers. The most commonly reported types of sandwiches were bacon, lettuce and tomato; and chicken salad sandwiches.

It was then assessed that UK-grown Apollo lettuce was identified as the likely contaminated ingredient. As a result, the three manufacturers undertook a precautionary voluntary recall.

Whole genome sequencing helped experts to link affected cases, revealing the scale of the large national outbreak. Amy Douglas, lead epidemiologist at the UK Health Security Agency said the outbreak demonstrated the crucial role that whole genome sequencing plays in "helping to detect and stop outbreaks more quickly than ever before".

Read more from Sky News:Meghan contacts estranged fatherIs this what the beginning of a war looks like? She set out how outbreaks involving fresh produce or ready-to-eat foods are particularly challenging due to the speed with which they emerge and the high number of cases that authorities must assess. Ms Douglas said: "By the time we are made aware of an outbreak, often none of the implicated food products are available for testing because they have either been eaten or disposed of, making it difficult to confirm whether they were contaminated." STEC 0145 was described by Douglas as a "growing threat which is now one of the most common types of Shiga toxin-producing E.

coli that we are detecting". There has been a significant rise in the number of UK E.coli cases over the past few years..