Cattle are considered the primary reservoir for STEC with multiple STEC serogroups isolated from both dairy and beef cattle (Cernicchiaro et al., 2013, Murinda et al., 2004 and Pradel et al., 2000). Estimates of the prevalence of STEC in herds of cattle vary widely from 4.6% to 55.9% (Cernicchiaro et al., 2013, Jenkins et al., 2003 and Renter et al., 2007). A multitude of factors modulates the colonization and persistent shedding of STEC in cattle. These include bacterial factors that K-Ras(G12C) inhibitor 12 affect the colonization of the recto-anal junction (RAJ), which likely allows the persistence and shedding of this pathogen for weeks or months (Jeong et al., 2013 and Naylor et al., 2003). Environmental factors, such as precipitation, temperature, soil characteristics, and presence of wild animals and insects are also believed to modulate the presence of STEC in the environment (Ferens and Hovde, 2011 and Shere et al., 2002). It has been recently shown that animal factors, including breeds and physiological differences may affect the prevalence of E. coli O157 in cattle ( Jeon et al., 2013).
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