Super shedders of EHEC

Last changed: 04 January 2023

Risk-factors for super-shedding of E. coli O157:H7 (VTEC O157) in cattle

E. coli O157:H7 (VTEC O157), a major pathogen causing serious disease in humans, is transmitted from cattle that carry the pathogen without showing symptoms. The transmission and resilience within cattle varies greatly but has been shown to depend on a small proportion of individuals that are colonized by the bacteria and shed high numbers. Eliminating these supershedders is therefore the key to decreasing the prevalence, as well as preventing transmission to humans. The necessary knowledge of why some individuals become super-shedders is still lacking. Unknown individual factors as stress, welfare and unbalanced microbiota have been pointed out as possible risk-factors but the associations with pathogen colonization and shedding are still largely unexplored. The aim of this study is to provide necessary understanding about the development of super-shedding and how it can be prevented.

The project consists of three parts: 1) a case control study, comparing herds with high presence of super-shedders with herds where the pathogen is mainly present in the environment, and will assess farm level riskfactors; 2) herds with high prevalence of VTEC O157 will be targeted to assess animal level factors, among which are indicators of poor animal welfare and stress; 3) the role of the gut microbiota in the development of super-shedders will be investigated. The project is interdisciplinary combining epidemiology, animal welfare, microbiology and molecular biology.

Contact: Ulf Emanuelson