Results of research in the United Kingdom suggest using E. coli vaccines in cattle could reduce the incidence of human sickness from E. coli O157 by as much as 85 percent.
Their research report, titled “Predicting the public health benefit of vaccinating cattle against Escherichia coli O157,” is published in the Proceedings of the National Academy of Sciences.
The authors note that E. coli O157, which can cause serious and sometimes fatal gastrointestinal illness, is difficult to control, partly due to poor understanding of of transmission dynamics across species boundaries. Vaccines for E. coli O157 in cattle are available but not widely used for a number of reasons:
Conflicting responsibilities of veterinary and public health agencies.
Clinical trials cannot easily test interventions across species boundaries.
Lack of information on the public health benefits.
The researchers examined transmission risk across the cattle–human species boundary and found three key results.
Supershedding of the pathogen by cattle is associated with the genetic marker stx2.
By quantifying the link between shedding density in cattle and human risk, we show that only the relatively rare supershedding events contribute significantly to human risk.
This finding has profound consequences for the public health benefits of the cattle vaccine.
“A naïve evaluation based on efficacy in cattle would suggest a 50 percent reduction in risk,” the authors note. “However, because the vaccine targets the major source of human risk, we predict a reduction in human cases of nearly 85 percent. By accounting for nonlinearities in transmission across the human–animal interface, we show that adoption of these vaccines by the livestock industry could prevent substantial numbers of human E. coli O157 cases.”