Key facts
- A national salmonella outbreak has been declared in the UK.
- One death and hundreds of illnesses have been reported.
- Imported eggs are the primary suspect, though not yet proven.
- Eating out appears to be a significant factor in transmission.
- Thorough cooking and good hygiene practices can prevent infection.
- Most cases are concentrated in England, but cases are spread across the UK.
The UK Health Security Agency (UKHSA) has declared a national outbreak of salmonella food poisoning, following one death and hundreds of reported illnesses. Imported eggs or products containing them are considered the most likely source, although this has not yet been definitively proven. Evidence also suggests that many infections occurred while people were dining out, pointing to catering and food services as potential transmission points.
Salmonella bacteria typically reside in the digestive tracts of animals like cattle, pigs, and chickens, making eggs and poultry common sources of infection. Transmission can occur through consuming improperly cooked contaminated food, drinking contaminated water, contact with infected animals, or cross-contamination in the kitchen. Symptoms include stomach cramps, diarrhoea, vomiting, and fever, usually appearing 12 to 72 hours after infection. While most people recover without medical intervention, vulnerable groups such as the elderly, infants, and those with weakened immune systems are at higher risk of severe illness, potentially requiring hospital care with fluids and antibiotics.
Genetic analysis of the bacteria indicates that the current infections are closely related, suggesting a common source. This genetic profile also shows similarities to a previous outbreak linked to imported eggs. Investigations involving 114 individuals in the current outbreak revealed that eggs provided the strongest signal as a potential cause. Some 24 cases were linked to five unnamed businesses, with 11 individuals reporting consumption of egg-containing dishes. These premises may source eggs from multiple suppliers, including imported ones. The UKHSA has stated there is no identified link to UK-produced eggs or poultry.
Food safety advice remains consistent: thoroughly cooked eggs handled hygienically pose minimal risk. Specific guidance recommends that infants, young children, pregnant individuals, and older adults should only consume runny or raw eggs if they bear the British Lion mark or are produced under the Laid in Britain scheme. Immunocompromised individuals should follow medical advice. Experts also suggest checking food hygiene ratings when choosing restaurants.
British eggs are protected by a successful hen vaccination program against salmonella strains, initiated in the mid-1990s, and the British Lion Scheme, established in 1998. The latter enforces strict codes including hen vaccination and traceability. Improved surveillance and detection have also contributed to safety. However, a significant number of eggs and egg products are imported, and these may not adhere to the same control standards, potentially carrying salmonella. Food businesses importing eggs are urged to verify their supply chains for vaccination information and completed food safety checks.
Key questions remain unanswered, including the definitive confirmation of eggs as the source, tracing the origin of imported eggs, and implementing measures to prevent further infections. The complexity of mixed sources for imported eggs presents a challenge. The UKHSA has notified other countries to investigate similar infections. While salmonella infections are common annually, large outbreaks linked to a single food source are unusual, prompting further scientific examination.