More than 450 people have fallen ill in a UK salmonella outbreak. We explain which eggs are safe, why older people are more vulnerable and when symptoms need medical attention.
The same strain of salmonella has now affected more than 450 people across the UK, according to government figures. Investigators have identified imported eggs used in restaurants, cafés and other catering businesses as a potential source, but the exact cause has not yet been confirmed. There is no evidence that UK-produced eggs are affected.
“Older people should be aware rather than alarmed,” says Dr Damien Tully, associate professor at the London School of Hygiene & Tropical Medicine. “We consume close to 40 million eggs a day in the UK and the overwhelming majority are eaten without any problems.”
Most infections clear within a week, but salmonella can cause more serious complications in older adults, particularly those who are frail or have underlying health conditions, adds Dr Tully.
Here’s what you need to know.
On 26 May, the UK Health Security Agency (UKHSA) identified an increase in infections caused by the same strain of Salmonella Enteritidis.
As of 13 August, it had confirmed 207 cases: 199 in England, six in Scotland, one in Wales and one in Northern Ireland. Patients range in age from under one to 90.
Most had a short-lived stomach illness. Among patients for whom hospital information was available, 38% were admitted to hospital; two developed bloodstream infections; and one death was associated with the outbreak. Milder cases may never be tested, notes Dr Tully, so this doesn’t mean 38% of everybody infected required hospital treatment.
“At the moment, there’s no evidence that this is some kind of salmonella ‘super-strain’ or that the strain itself is unusually severe,” he says.
The UKHSA states that of the 114 patients interviewed, 95 said they had eaten food prepared outside the home in the week before their symptoms began. Investigators identified five food businesses visited by two or more unrelated patients, linking 24 cases in total.
By 27 August, an additional 259 cases were reported by the UKHSA, with two new clusters identified, bringing the total to 474.
Not quite. Genetic testing shows that the strain is closely related to one involved in a separate outbreak in 2025, which affected 123 people and was linked to imported eggs.
“This raises the possibility of a recurring or persistent source of contamination somewhere in the food supply chain, although we can’t yet say that the two outbreaks have the same source,” says Dr Tully.
The UKHSA identifies older adults as a higher-risk group, although age alone doesn’t make someone vulnerable.
It’s down to a combination of factors, says Dr Tully. As we age, our immune system becomes less effective, underlying conditions become more common and the body may struggle to replace lost fluid and salts, he explains.
“In older adults, dehydration and acute kidney injury can develop more quickly,” adds Dr Deepali Misra-Sharp, an NHS GP in Glasgow. Acute kidney injury means a sudden reduction in kidney function.
The gut’s physical defences change, too. “When we age, the cells that line the gastrointestinal tract are weaker, which can allow more salmonella cells to leave the gastrointestinal tract,” says explains Dr Anthony Buckley, associate professor in gut microbiology at the University of Leeds. The bacteria can then enter the bloodstream and spread around the body, potentially causing life-threatening sepsis, says the UKHSA.
Previous UK research found that adults over 65 were more likely than younger adults to develop serious bloodstream infections, explains Dr Tully. People with diabetes, chronic kidney disease, heart failure, a weakened immune system, dementia or frailty are particularly vulnerable, adds Dr Misra-Sharp.
The FSA describes the salmonella risk from British Lion and Laid in Britain hen eggs as “very low”. They come from vaccinated hens and are produced under strict testing, hygiene and traceability rules, says Professor Paul Wigley, an expert in animal microbial ecosystems at the University of Bristol. More than 90% of UK eggs are produced under the Lion scheme, according to the British Egg Industry Council.
Salmonella Enteritidis, the type causing the current outbreak, can enter an egg while it forms inside the hen, explains Professor Wigley. A clean, unbroken shell is therefore no guarantee that an egg is free of salmonella.
The Food Standards Agency (FSA) advises older adults and people with underlying health conditions to ensure that any eggs eaten outside the home are thoroughly cooked because the eggs may not be British Lion or Laid in Britain assured.
This means avoiding runny eggs and dishes made with fresh raw or lightly cooked egg, such as fresh mayonnaise, hollandaise, mousse and soufflés.
Dr Lisa Ackerley, a chartered environmental health practitioner and food hygiene expert, also advises checking when eating out, saying many businesses only use British Lion eggs. She recommends asking whether a restaurant uses them and to see them.
She adds that factory-made mayonnaise and similar products often use pasteurised liquid egg, but freshly made versions may not.
The official advice is to choose eggs that are thoroughly cooked when eating out.
Older adults and people with underlying conditions can still eat raw or runny hen eggs at home if they carry the British Lion mark or were produced under the Laid in Britain (LIB) scheme, says the FSA.
Yet even Lion eggs should be handled hygienically.
To be on the safe side:
If you don’t have British Lion or LIB eggs – if, for example, you have bought unlabelled eggs from a farm shop – it’s best to cook them thoroughly, particularly if you’re older or have an underlying condition. This kills harmful bacteria, says the FSA.
“Thoroughly cooked” means that both white and yolk would be solid, adds Dr Ackerley. Flip a fried egg so that both sides cook; scrambled eggs and omelettes should not be wet in the middle.
If you’re severely immunocompromised, follow your clinical team’s advice.
Ducks, geese and quail are not generally covered by the same salmonella vaccination and assurance arrangements as British Lion hens, says Professor Wigley. The FSA therefore advises cooking both white and yolk until solid.
“Symptoms of a salmonella infection include diarrhoea, stomach cramps and sometimes vomiting and fever,” says Hannah Charles, the UKHSA’s lead epidemiologist for gastrointestinal infections.
The UKHSA also lists nausea, headache and loss of appetite. Symptoms usually begin 12 to 72 hours after infection and last for four to seven days.
Older adults generally experience the same stomach symptoms. But in someone who is frail or has cognitive impairment, these may be “mild, delayed or occasionally absent,” says Dr Misra-Sharp. The first sign may be acute confusion, a sudden loss of mobility, a fall, lethargy or low blood pressure, she explains.
“Treatment for most patients consists of fluids and rest,” says Professor Owen Spiller, head of medical microbiology at Cardiff University. He explains that antibiotics are generally reserved for severe infection, cases that spread beyond the gut and people at greater risk of complications, including older people and those with underlying conditions.
The NHS says that most food poisoning can be managed at home. Rest, take small, frequent sips if you feel nauseous and eat when you feel able, avoiding fatty or spicy food if it makes your symptoms worse. A pharmacist can recommend oral rehydration sachets.
If you have heart failure, serious kidney disease or a prescribed fluid restriction, ask your GP or NHS 111 how much to drink, says Dr Misra-Sharp. Don’t change a fluid restriction without advice.
Call 111 or ask for an urgent GP appointment if you can’t keep fluids down, have bloody diarrhoea, remain dehydrated after using rehydration sachets, have diarrhoea for more than seven days or have vomited for more than two days, says the NHS. Dark urine, much less urine, persistent dizziness, unusual tiredness, fast breathing or a racing heart can signal serious dehydration.
Older or frail people should seek help earlier, says Dr Misra-Sharp. People who take water tablets, certain blood-pressure or heart medicines or anti-inflammatory painkillers, should contact their GP or call 111 if they become dehydrated. The medicines may need reviewing, but don’t stop them without medical advice.
Call 999 or go to A&E if you or someone else has sudden severe abdominal pain, severe breathing difficulty, pale, blue-grey or blotchy skin, or confusion or fails to respond as usual, says the NHS. Dr Misra-Sharp also flags marked drowsiness or collapse. These can indicate severe dehydration, invasive infection, sepsis or shock, she says.
Salmonella usually reaches the gut in contaminated food or water, says the UKHSA. It can breach the gut’s protective mucus and invade cells in the intestinal lining, explains Dr Buckley.
The resulting inflammation draws fluid into the gut, causing diarrhoea, while fever is part of the immune response, he says. In severe cases, the bacteria can enter the bloodstream.
“People can continue to carry and shed salmonella in their stools even after they start to feel better,” says Dr Tully. This can last several weeks, although the risk is greatest while they have diarrhoea.
Wash your hands with soap and water after using the toilet and before preparing or eating food. Don’t prepare food for other people while unwell and keep toilets and frequently touched bathroom surfaces clean, Dr Tully advises.
Stay at home and rest. If you have a high temperature or feel too unwell for your normal activities, avoid contact with other people until you feel better, says the NHS. If you work, don’t return until you’ve been free from diarrhoea and vomiting for at least 48 hours. Wash soiled clothes or bedding separately on a hot wash and don’t share towels or cutlery.
British Lion and Laid in Britain eggs remain very low risk and the FSA’s advice on eating them has not changed.
“Don’t worry too much and don’t stop eating eggs [with the Lion mark],” says Dr Ackerley.
Just remember that anyone aged over 65, pregnant women, under-fives and those with underlying health conditions are currently advised by the FSA to choose thoroughly cooked eggs when eating in restaurants, cafés or ordering takeaway.
Check the FSA’s updated salmonella advice for the latest guidance.
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