At least 86 people have now been admitted to hospital as a result of an E. coli outbreak linked to lettuce, health officials said.
Figures from the UK’s Health Safety Agency show there were 45 more cases of the infection by Tuesday this week, bringing the UK’s confirmed death toll to 256.
All those affected first developed symptoms before May 31.
UKHSA said: “Although the number of cases has now slowed, we expect this number to rise as NHS laboratories send samples to UKHSA for genomic sequencing which may link cases to this focal strain.”
Several food manufacturers have recalled sandwiches, wraps and salads sold in major supermarkets and retail chains over fears they are linked to the outbreak.
The Food Standards Agency said lettuce used in the products was considered the likely source of the outbreak.
All reported cases involve Shiga toxin-producing E. coli O145 (Stec).
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Streptococcus is often transmitted by eating contaminated food, but it can also be spread by close contact with an infected person, as well as direct contact with an infected animal or where it lives.
Darren Whitby, head of incidents at the FSA, said: “Several sandwich manufacturers have now taken precautionary measures to recall and recall a variety of sandwiches, wraps, soups and rolls as the food chain and epidemiological links have allowed us to narrow down the wide range of foods consumed. to the small number of lettuce leaves that were used in these products.
“This remains a complex investigation and we continue to work closely with the relevant businesses and local authorities to ensure the necessary steps are taken to protect consumers.
“While we are confident that the source of the outbreak is related to a small number of lettuce leaves, which we identified early on through extensive food chain analysis, work continues to identify the root cause of the outbreak with growers, suppliers and manufacturers. that steps can be taken to prevent recurrence.
“We will remain vigilant until the root cause of the outbreak is confirmed and will keep an open mind about possible causes of the outbreak.”
People are advised to call NHS 111 or contact their GP if they are concerned about a child under 12 months, a child stops breastfeeding or bottle-feeding when they are ill, a child under five has signs of dehydration such as less wet diapers.
You should also call NHS 111 or contact your GP if older children or adults still have signs of dehydration after using oral rehydration bags.
Those showing symptoms of infection should contact NHS 111 or their GP.