Enterohaemorrhagic E. coli O157:H7 was first implicated inhuman disease in the early 1980s, with the ruminants cited asthe primary reservoirs. Preliminary studies indicated cattle to bethe sole source of E. coli O157:H7 outbreaks in humans, however,further, epidemiological studies have demonstrated that E. coliO157:H7 was widespread in other food sources and that a numberof transmission routes existed.