Understanding the transmission dynamics of O157:H7 super-shedding infections in feedlot cattle.

Background: The presence of O157:H7 ( O157:H7) super-shedding cattle in feedlots has the potential to increase the overall number (bio-burden) of O157:H7 in the environment. It is important to identify factors to reduce the bio-burden of O157 in feedlots by clarifying practices associated with the occurrence of super-shedders in feedlot cattle.

Methods: The objective of this study is to (1) identify host, pathogen, and management risk factors associated with naturally infected feedlot cattle excreting high concentrations of O157:H7 in their feces and (2) to determine whether the ingested dose or the specific strain of O157:H7 influences a super-shedder infection within experimentally inoculated feedlot cattle.

Comparative Pathogenicity of Wildlife and Bovine O157:H7 Strains in Experimentally Inoculated Neonatal Jersey Calves.

Shiga toxin-producing , like O157:H7, are important human and animal pathogens. Naturally-acquired O157:H7 infections occur in numerous species but, particularly, cattle have been identified as a significant reservoir for human cases. O157:H7 are isolated from a number of domestic and wild animals, including rodents that share a living space with cattle.