While studying campylobacteriosis cases, the research team found that 97 pct of the cases in Lancashire, UK, were caused by bacteria typically found in chicken and livestock.
The study was based on DNA-sequence comparison of thousands of bacteria collected from human patients and animal carriers.
The research team led by Daniel Wilson, of the University of Chicago, and formerly Lancaster University, United Kingdom, sequenced the DNA of bacteria collected from 1,231 patients and compared it to Campylobacter jejuni DNA sequences collected from wild and domestic animals, and the environment.
They used evolutionary modelling to trace the ancestry of human C. jejuni back to one of seven source populations.
The team found that in 57 percent of cases, the bacteria could be traced to chicken, and in 35 percent to cattle. Wild animal and environmental sources were accountable for just three percent of disease.
"The dual observations that livestock are a frequent source of human disease isolates and that wild animals and the environment are not, strongly support the notion that preparation or consumption of infected meat and poultry is the dominant transmission route," said Wilson.
The study appears in the open-access journal PLoS Genetics.