UK Salmonella Outbreak Linked to Imported Eggs, UKHSA Investigates

A growing outbreak of salmonella has sickened more than 200 people across the United Kingdom, the UK Health Security Agency (UKHSA) said on Tuesday. The agency is investigating the cases and says that imported eggs or dishes containing eggs are the leading suspects. Most infections appear to have occurred while people were eating out, rather than at home, pointing to restaurants, cafés and take‑away outlets as potential sources.

The outbreak, which has affected England, Scotland, Wales and Northern Ireland, began in late March and has now produced 229 confirmed cases. Whole‑genome sequencing of the bacteria taken from patients shows that the strains are closely related, with only a handful of genetic differences. The analysis indicates that all cases are part of the same outbreak and that the bacteria have a common source, most likely linked to imported eggs. UKHSA has found links to five unnamed businesses or food outlets where diners reported eating dishes containing eggs.

Salmonella bacteria normally live harmlessly in the digestive tracts of animals such as cattle, pigs and chickens. The bacteria are shed in faeces and can contaminate eggs and poultry. People typically catch the infection by eating food that has not been cooked properly, drinking contaminated water, or coming into contact with infected animals or cross‑contaminated kitchen surfaces. Person‑to‑person spread is rare. Symptoms—stomach cramps, diarrhoea, vomiting or fever—usually appear 12 to 72 hours after infection. Most people recover without treatment, but older adults, babies, pregnant women and those with weakened immune systems are at higher risk of severe disease and may require hospital care with fluids and sometimes antibiotics.

The Food Standards Agency has issued guidance to catering businesses on the storage and handling of eggs. The agency also noted that the majority of recent cases have not been linked to food that was cooked at home. “At this time there is no identified link to UK‑produced eggs or poultry,” the UKHSA said. “The standard advice remains unchanged – thoroughly cooked eggs that are handled hygienically should not present a food safety risk.”

Experts say that the vaccination of commercial hens against common salmonella strains, which began in the mid‑1990s, has been a major public health success. Dr Charlotte Hammer of the University of Cambridge said the vaccination and the British Lion scheme – a code of practice for egg producers that includes vaccination, regular testing and a passport system – have substantially reduced egg‑associated salmonella infections. “We do still import a large number of eggs and egg products, and salmonella could be contained within these because the countries in which they're produced don’t use that same level of control,” added Professor Paul Wigley of the Bristol Veterinary School.

The UKHSA is continuing to interview confirmed cases and is carrying out tests on businesses likely to be involved. Local authorities are also conducting opportunistic testing. The agency is examining the entire supply chain, looking at where the eggs or egg products were sourced, stored and served. Once enough information is gathered, the next step will be to trace the exact source and country of origin, and to limit further infections.

Dr Kathleen O’Reilly of the London School of Hygiene and Tropical Medicine recommends checking food hygiene ratings when choosing cafés or restaurants. The UKHSA has alerted other countries about the outbreak so they can check for any genetically similar infections. While salmonella infections occur every year in the UK, outbreaks that grow this quickly are relatively unusual, said Dr Gauri Godbole of the UKHSA, who said scientists will examine the factors that led to this situation.

Anyone experiencing symptoms should contact their GP or an out‑of‑hours service. The UKHSA urges people to keep food safe by cooking eggs thoroughly, washing hands before and after handling food, and following proper food hygiene practices. The investigation continues, and the agency will update the public as new information becomes available.