A 2003 study on the prevalence of E. coli O157:H7 in livestock at 29 county and 3 large state agricultural fairs in the United States found that E. coli O157:H7 could be isolated from 13.8 percent of beef cattle, 5.9 percent of dairy cattle, 3.6 percent of pigs, 5.2 percent of sheep, and 2.8 percent…