In response to a recommendation of the Public Inquiry into the 2005 E.coli O157 outbreak in South Wales (‘The feasibility of identifying “supershedder” cattle on-farm should be explored as a potential means of reducing the likelihood of spreading E.coli O157 to other cattle.'), The FSA in Scotland hosted a workshop in November 2011 titled: 'Understanding the factors that lead to Enterohaemorrhagic E.coli (EHEC) colonisation in cattle and the role of supershedding in the transmission and maintenance of infection.' The experts who attended the workshop made a number of recommendations on the key research gaps in relation to our understanding of EHEC supershedding by cattle.
The objectives for this study are to:
- determine shedding and transmission dynamics of specific PT21/28 and PT32 strains. These colonisation trials will study bacterial and host factors associated with supershedding
- undertake a comprehensive genetic comparison of human and bovine EHEC O157 strains from England, Wales and Scotland. This will involve a new survey of 270 farms and archives from previous farm surveys. A minimum of 500 human and bovine samples will be analysed by Whole Genome Sequencing (WGS)
- use output data to create guidelines for models of on-farm interventions to determine the methods that have the greatest potential of reducing human illness.
- determine the effectiveness of a practical and modelled intervention on the control of supershedding
The project is an extensive multi-disciplinary and muiti-centre programme to address the need to more clearly define the definition of a 'supershedder'. This will improve our understanding of the dynamics of E.coli O157 excretion by cattle (in terms of the duration of shedding, the levels excreted, and the frequency by which an animal can become a supershedder), and show how high-shedding animals’ impact on the contamination of the foodchain, the environment and levels of human illness. The project will help us to understand how effective an on-farm intervention for the control of VTEC would have to be in order to have an impact on human health and which intervention strategies should be trialled for future control of E.coli O157 shedding on UK farms.