The research team, lead by scientists at the University of Glasgow, examined data from a range of sources to assess the risk of transmission of E. coli O157 from cattle to humans and to estimate the potential benefits of vaccinating cattle against the pathogen.
The results showed that one of the main factors in the transmission of infection from cattle to humans is so -called ‘super-shedding’, where cattle excrete very high numbers of bacteria in their faeces for a limited period, but show no symptoms of infection. Super-shedding was also found to be associated with the stx2 genetic marker.
When super-shedding is factored into the evaluation of the benefits of cattle vaccination, it raises the estimate of the reduction in risk from 50% to 85%. The study’s authors suggest that this means that cattle vaccination could prevent many human cases of E. coli O157 infection, because it targets the major source of risk.
Although cattle vaccines against the pathogen exist, they are little used for a variety of economic and other reasons, but these findings may help to increase the adoption of vaccination by the livestock industry.
The study is published in the online journal PNAS and can be found in full here.