Researchers identify virulent avian E. coli strain is behind serious UK outbreak in farmed turkeys

Scientists from the University of Surrey and the University of Bristol – working with the United Kingdom Poultry Health Services – have identified a previously unreported Avian Pathogenic Escherichia coli strain as the dominant cause of a major turkey disease outbreak in the UK, highlighting the urgent need for broad-spectrum vaccines

Although generally harmless certain strains of Escherichia coli (E. coli) bacteria – known as Avian Pathogenic E. coli (APEC) – can cause severe illness in poultry and result in significant economic losses to farmers and broader animal welfare concerns. Researchers from the University of Surrey and the University of Bristol, in collaboration with UK Poultry Health Services, have now determined why different APEC strains behave with variability in disease outbreaks.

The study analysed a colibacillosis outbreak in turkeys in the UK and found that a strain designated ST-101 was responsible for nearly 60 per cent of cases. This strain had not previously been reported as the principal cause of a turkey outbreak in the country.

The Surrey research team from, led by Dr Jai Mehat, Dr James Adams and Professor Roberto La Ragione, compared the behaviour of ST-101 with several other high-risk APEC strains. They found that ST-101, ST-95, and ST-140 were particularly effective at invading and surviving within chicken gut cells and macrophages, which are key components of the immune system.

By contrast, the ST-23 and ST-117 strains were less able to invade host cells. However, despite this apparent disadvantage, ST-117 proved to be the most lethal in an insect infection model. This finding suggests that APEC strains use distinct mechanisms to cause disease, even when they share similar genetic features.

“Our research shows that a one-size-fits-all approach to controlling Avian Pathogenic E. coli infections is not effective.

“Current vaccination strategies often target specific strains, but they may not protect against emerging APEC threats. Therefore, we need to develop novel vaccines that can target a range of APEC strains,” said Dr Mehat, senior author of the study and a lecturer in Molecular Bacteriology at the University of Surrey.

“We extrapolate that broad-spectrum control measures, including the induction of trained immunity in chickens to combat diverse strains, offer more effective protection,” said Professor Shahriar Behboudi, co-author and Professor in Correlates of Immune Protection at the University of Bristol.

“Existing vaccines typically focus on individual strains and may fail against emerging APEC variants,” he added.

Dr Sara Perez, co-author and Clinical Director at Poultry Health Services said: “Infections caused by APEC are a foremost threat to farmed poultry and to safeguard animal welfare and food safety, we must increase our surveillance of poultry flocks and improve our understanding of the presence and evolution of APEC strains.”

For further reading please visit: 10.1080/21505594.2025.2546682