An outbreak of E. coli thought to be linked to nationally-distributed food has led to people being admitted to hospital, the UK Health Security Agency (UKHSA) has said.

Whole genome sequencing of samples indicates that most of the 113 cases reported across the UK since May 25 “are part of a single outbreak”, the UKHSA said.

A statement added: “Based on the wide geographic spread of cases, it is most likely that this outbreak is linked to a nationally distributed food item or multiple food items.”

The UKHSA said it was working with public health agencies in Scotland, Northern Ireland and Wales, the Food Standards Agency (FSA) and Food Standards Scotland to determine the cause of people’s illness.

All the cases recorded in the outbreak involve Shiga toxin-producing E. coli O145 (Stec), with 81 cases in England, 18 in Wales, 13 in Scotland and one person in Northern Ireland who believes they acquired Stec in England.

The people who have fallen ill range in age from two to 79, with the majority of cases in young adults.

The number of people affected is expected to rise.

Of the 81 people identified so far in England, 61 have provided information to UKHSA related to food, travel and potential exposures.

Of these 61 people, 61% have been admitted to hospital.

E. coli are a diverse group of bacteria that are normally harmless and live in the intestines of humans and animals.

However, some strains produce toxins that can make people very ill, such as Stec.

People infected with Stec can suffer diarrhoea, and about 50% of cases have bloody diarrhoea.

Other symptoms include stomach cramps and fever.

Symptoms can last up to two weeks in uncomplicated cases.

Some patients, mainly children, may develop haemolytic uraemic syndrome (HUS) which is a serious life-threatening condition resulting in kidney failure.

A small proportion of adults may develop a similar condition called thrombotic thrombocytopaenic purpura (TTP).

Stec is often transmitted by eating contaminated food but can also be spread by close contact with an infected person, as well as direct contact with an infected animal or where it lives.

The UKHSA said there was currently no evidence linking the outbreak to open farms, drinking water or swimming in contaminated sea, lakes or rivers.

Trish Mannes, incident director at UKHSA, said: “If you have diarrhoea and vomiting, you can take steps to avoid passing it on to family and friends.

“NHS.uk has information on what to do if you have symptoms and when to seek medical advice.

“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.”

Darren Whitby, head of incidents and resilience at the FSA, said it was working to identify the source of the illness “which is likely to be linked to one or more food items”.

People are advised to call NHS 111 or contact their GP surgery if they are worried about a baby under 12 months, a child stops breast or bottle feeding while they are ill, a child under five has signs of dehydration such as fewer wet nappies, and if older children or adults still have signs of dehydration after using oral rehydration sachets.

Help should also be sought if people are being sick and cannot keep fluid down, there is bloody diarrhoea or bleeding from the bottom, diarrhoea lasts more than seven days or vomiting for more than two days, the UKHSA said.