The bacteria, which cause severe gastrointestinal illness and even death in humans, are spread by consuming contaminated food and water, or by contact with livestock faeces in the environment. Cattle are the main reservoir for the bacterium.
The study, published online in the journal PNAS, used veterinary, human and molecular data to examine the risks of E. coli O157 transmission from cattle to humans, and to estimate the impact of vaccinating cattle.
The risk of E. coli O157 infection is particularly significant when the cattle are 'super-shedding' – excreting extremely high numbers of bacteria in their faeces for a limited period of time. Vaccines against the bacteria exist that can reduce super-shedding. As a consequence, the researchers predict that vaccinating cattle could reduce human cases by nearly 85%, far higher than the 50% predicted by studies simply looking at the efficacy of current vaccines in cattle.
The research was led by a team of researchers at the University of Glasgow in collaboration with the University of Edinburgh's The Roslin Institute, the Royal Veterinary College, Scotland's Rural College, Health Protection Scotland, and the Scottish E. coli O157/VTEC Reference Laboratory.
Prof. David Gally at The Roslin Institute, who collaborated on the research, stated: "Our study also shows that E. coli producing the toxin type that causes the most serious and potentially lethal symptoms in humans is also associated with super-shedding from cattle. The more we discover about how the bacteria colonise cattle, the more we are able to target these processes to improve vaccines".
Research is ongoing in Scotland by the same collaborative group to develop better vaccines against E. coli.
The study took place thanks to BBSRC's strategic funding to The Roslin Institute and The Pirbright Institute. Funding also came the Wellcome Trust International Partnership Award in Veterinary Epidemiology, and the Foods Standards Agency Scotland.
The full article is published in PNAS and can be accessed here.