UK Study Links Industrial Poultry Farming to 100-Fold Surge in Campylobacter Transmission

A genomic study from the Ineos Oxford Institute and the University of Oxford has found that industrial poultry farming has driven a more than 100-fold increase in Campylobacter transmission between hosts, accelerating the spread of a pathogen already responsible for more human diarrhoeal disease than any other bacterium — and doing so as antimicrobial resistance narrows treatment options.

Industrial poultry farming has accelerated the evolution and spread of Campylobacter, according to a genomic study from the Ineos Oxford Institute for antimicrobial research and the University of Oxford.

The researchers say transmission between hosts has risen by more than 100-fold, allowing strains that once circulated largely in wild birds to mingle widely within commercial flocks. That matters because Campylobacter is the world’s leading bacterial cause of diarrhoea, and antimicrobial resistance is making some infections harder to treat.

The team analysed nearly 2,800 genomes from chickens and wild birds sampled in 30 countries between 1979 and 2024. Their work suggests that the explosive growth of poultry production has created ideal conditions for the bacterium to diversify and adapt. Global chicken numbers have increased roughly seven-fold since the 1960s, to about 31 billion birds.

The study also points to genetic changes associated with life in chickens, including traits linked to drug resistance, stress tolerance, metal acquisition and motility. The authors argue that densely packed flocks may act as “pathogen sponges”, drawing in strains from multiple sources and helping them persist.

Earlier work from the institute found that many human Campylobacter infections in Oxfordshire were linked to poultry meat and often carried antibiotic resistance. The broader message is clear: farming systems are now shaping microbial evolution as much as biology is.

Reference: O.J. Kyne, B.S. Penman, D.J. Kelly, & S.K. Sheppard: Accelerating Campylobacter zoonosis in the Anthropocene, Proc. Natl. Acad. Sci. U.S.A. 123 (32) e2609969123.
https://doi.org/10.1073/pnas.2609969123 (2026).