Some 113 people have become ill with E. coli in recent weeks and experts believe it is most likely linked to a nationally distributed food item.
The UK Health Security Agency says testing of samples suggests all of the cases since 25 May are “part of a single outbreak”.
Based on the wide geographic spread, it is likely a contaminated batch of product that people can buy around the UK.
A number of foods have carried E.coli before, including beansprouts, pre-packed salads and undercooked meat.
In the New Year some Lancashire cheese was recalled as a precaution after an E. coli death, but later testing revealed no evidence of a link.
The source of current outbreak is not yet confirmed or known. Consumers will be told if there is a food identified.
There is currently no evidence linking the outbreak to other potential E.coli sources such as petting farms, drinking water or swimming in contaminated sea, lakes or rivers, say the officials investigating it.
A number of foods have carried E.coli before, including beansprouts, pre-packed salads and undercooked meat.
The number affected is expected to rise as more samples from patients get tested.
So far, there have been:
81 cases found in England18 in Wales13 in Scotland1 in Northern Ireland
The youngest who has become ill is aged two and the oldest aged 79. The majority though have been young adults and some have been in hospital.
Symptoms include severe and sometimes bloody diarrhoea, stomach cramps, vomiting and fever.
It usually takes a few days from being infected for symptoms to show.
Most people recover well, but some – such as young children – can become very unwell. Call NHS 111 or contact your GP surgery if you are worried.
E. coli are a diverse group of bacteria that normally live in the intestines of humans and animals.
Although many are harmless, some produce toxins that can make you sick.
This outbreak is a Shiga toxin-producing E. coli (STEC).
There are things people can do to reduce the risk of infection.
Trish Mannes, Incident Director at UKHSA, said: “Washing your hands with soap and warm water and using disinfectants to clean surfaces will help stop infections from spreading.
“If you are unwell with diarrhoea and vomiting, you should not prepare food for others while unwell and avoid visiting people in hospitals or care homes to avoid passing on the infection in these settings.
“Do not return to work, school or nursery until 48 hours after your symptoms have stopped.”
Alcohol-based hand gels will not stop E. coli.
In March, rowers taking part in the 2024 Boat Race between Oxford and Cambridge in London were told not to enter the Thames after high levels of E. coli were found.
