Many animals carry this bacterium. Horses are a particular danger because children and adults have a particular fondness for patting and stroking them; other farm animals may be similarly infectious.
It is estimated that in an average year in the UK, 1000 cases of E-coli-157 are reported. Most are mild.
The strain E. coli O157:H7 kills 60 people a year in the USA alone. It produces toxins that cause bloody diarrhoea and can lead to kidney failure. It is likely to be more common in cattle and, following slaughter, in beef meat than previously thought. In one study, more than 80 percent of 900 calves tested had already been exposed to it, and in 13 of 15 herds tested at least one animal was infected.