More than 50 new cases of salmonella have been identified in the last week amid three major outbreaks linked to imported eggs, health officials have said.
The UK Health Security Agency (UKHSA) has today confirmed a total of 528 cases – a jump from 474 last Thursday.
Some 305 infections have been recorded in the current outbreak, up from 259 this time last week, and one person has died.
Another death has been recorded in a cluster with 41 cases, while the remaining 182 infections have been linked to a third spread.
Investigations are ongoing but health chiefs believe imported eggs are the likely culprit.
British cases so far have been linked to eating out at 'small cafes, restaurants and takeaway businesses,' the UKHSA said.
And as public health officials rush to identify the source, cases have also been reported in Austria, Belgium, Denmark, France, Germany and the Netherlands.
More than 50 cases of salmonella have been identified in the last week amid three major outbreaks linked to imported eggs, health officials have said
While the UKHSA has identified a 'link to imported eggs', Dutch health officials have investigated chicken products as a possible source of infection.
Food safety chiefs are urging Britons to avoid 'raw or lightly cooked egg' products such as mousses, mayonnaise or hollandaise sauce.
Vulnerable groups – including over-65s, pregnant women and under-fives – are also advised to avoid runny eggs when eating out.
Officials say there is no evidence that eggs produced in the UK pose any threat.
Salmonella is typically caught by eating contaminated food such as poultry, meat, eggs, raw fruit and vegetables and unpasteurised dairy products.
Symptoms include stomach cramps and diarrhoea, and it can lead to severe dehydration, blood poisoning, organ failure and even death.
Those most at risk of fatal complications include infants, pregnant women, the elderly and those with weakened immune systems.
More than a third of patients in the three outbreaks have required hospital treatment.
Most cases have been recorded in recent weeks and months, but the samples date back as far as August last year.
Hannah Charles, lead epidemiologist at UKHSA, said: 'We continue to work closely with the Food Standards Agency and other public health partners to investigate these Salmonella clusters.
'Our investigation to date indicates a link to imported eggs, however this investigation remains ongoing. We will continue to follow up cases and investigate any further common sources if they come to light.
She also stressed that the overall risk to the public 'remains low'.
Professor Ian Young, chief scientific adviser for the Food Standards Agency said: 'Our food safety advice remains the same: eggs that are thoroughly cooked and handled hygienically should not present a food safety risk.
'Infants, young children, pregnant people and older adults should only eat raw or lightly cooked eggs if they carry the British Lion mark or are produced under the Laid in Britain scheme.
'This advice does not apply to those who are severely immunocompromised and require medically supervised diets, who should continue to follow individual medical advice.
'If you're eating out or buying food that contains eggs, you may not know if these carry the British Lion mark or are Laid in Britain assured.
'If this is the case, when eating out the safest approach for vulnerable people is to ensure they're thoroughly cooked and to avoid dishes containing raw or lightly cooked egg, such as mousses, fresh mayonnaise or hollandaise sauce.
'As with any foodborne illness, good hygiene remains your best protection: store and cook food according to the packet instructions, wash your hands thoroughly before handling food and always after handling raw meat, poultry and eggs.'
Commercial hens which produce eggs sold in UK supermarkets are vaccinated against the most common strains of salmonella, making it unlikely that any outbreak would start in Britain.
But salmonella cases have been on the rise in the UK. Last year, there were 10,406 recorded cases – the highest in a decade.
One of the greatest dangers once salmonella reaches the bloodstream is sepsis – when the body's response to infection begins damaging its own tissues and organs.
It affects 245,000 Britons and kills almost 50,000 each year.
Symptoms include confusion, extreme shivering, severe breathlessness, passing little or no urine and mottled or bluish skin. An overwhelming sense of 'impending doom' can also be a red flag.
Sepsis requires urgent hospital treatment with antibiotics and, where needed, intravenous fluids and oxygen. Severe cases may require intensive care.