The UK Health Security Agency (UKHSA) has been investigating a nationwide Salmonella Enteritidis outbreak that has sickened more than 200 people. The vehicle of illness has not yet been definitively confirmed, but epidemiological evidence points to egg consumption as the strongest food signal identified to date.

A total of 207 cases have been confirmed as of August 13, with sample dates ranging from August 11, 2025–August 1, 2026. Of these, 206 cases were reported in 2026. July has seen the largest number of cases.

Whole genome sequencing (WGS) revealed that all cases belonged to the same five-single-nucleotide polymorphism (SNP) single-linkage cluster, indicating a common source of contamination.

UKHSA identified the outbreak on May 26 after detecting an increase in infections caused by a single S. Enteritidis strain using WGS data. Evidence gathered to date has suggested that the outbreak is not associated with international travel, as only six of 207 patients reported traveling outside the UK.

Cases have been reported in England (199), Scotland (six), Wales (one), and Northern Ireland (one). In England, London accounts for the most cases (47), followed by Yorkshire and Humber (38). Patients range in age from less than 1 year–90 years, with a median age of 30, and 51 percent are female.

Most patients experienced self-limiting gastrointestinal illness. However, among patients for whom information was available, 38 percent were hospitalized, two people developed bloodstream infections, and one has died.

Egg Consumption is Strongest Food Signal

Of 114 patients who completed regional or outbreak questionnaires, 95 (83 percent) reported eating food prepared outside the home during the week before symptom onset. Interviews identified five food businesses that had been visited by two or more unrelated patients, collectively linking 24 cases.

Of interviewed patients, 11 reported eating dishes made with eggs, making egg consumption the strongest signal in the investigation, per UKHSA.

Food chain investigations found that the implicated businesses were supplied with eggs from multiple sources, including egg importers. Local investigations also identified possible cross-contamination risks at two of the establishments. At present, investigators have identified no link to UK-produced eggs or poultry.

The UK Food Standards Agency (FSA) has been working with local authority environmental health teams, which have provided food safety management advice to businesses where issues were identified.

Outbreak Genetically Linked to 2025 Imported Egg Outbreak

The outbreak strain was phylogenetically linked, within 25 SNPs, to a 2025 S. Enteritidis outbreak that was also associated with imported eggs.

UK officials have been compiling information from the outbreaks to investigate potential risks associated with imported eggs and determine whether preventive measures are necessary.

UKHSA also used the European Center for Disease Prevention and Control's EpiPulse platform to notify member countries and determine whether genetically related S. Enteritidis cases have been detected elsewhere.

Epidemiological and food chain investigations are ongoing to identify the source and origin of the contamination.