Control of E-coli O157 (VTEC) by applied management practices

Ellis-Versen, J and Van Winden, S C L (2008) Control of E-coli O157 (VTEC) by applied management practices. CATTLE PRACTICE, 16. p. 54.

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Abstract

The control of zoonotic pathogens in animal produce can occur in several steps along the food chain. However, only reduction at farm level will reduce the risk posed by the environment and by direct contact with farm animals. Farmers have a key role to play in food safety, especially when a farm is open to the public. This is formalised in EU and UK legislation, placing the accountability for food safety on livestock farmers. This emphasises the need for systematic and documented control measures implemented at the farm level. Good herd health plans can provide the farmer with a standardised approach to control for zoonotic agents. This study identified several good management practices, which if applied systematically, can reduce the prevalence of E. coli O157 (VTEC) in young cattle. Management practises, which were associated with low herd prevalence of VTEC, were identified using a randomised controlled trial on cattle farms in England and Wales (Ellis-Iversen et al. 2008). The farmers were contacted through veterinary practices that use the Veterinary Laboratories Agency (VLA) for diagnostic testing. Initially, 411 farms were contacted and 255 were visited and sampled. Exclusion criteria were: no VTEC cultured at first visit, herd size <60 in total or <20 young-stock, positive TB status and public side-enterprises such as B&Bs or open farms. The remaining 54 farms were randomly allocated either to apply a package of specified biosecurity and hygiene practices (intervention farms) or to continue their usual practices (control farms). The within farm prevalence of VTEC and compliance with allocated practices were then observed in young-stock on each farm over a period of 4.5 months. Multivariable population-averages-based statistical models were used to assess the effect of the package of control measures on the proportion of positive samples and adjust for compliance. Throughout the study, the prevalence decreased in all groups, but VTEC prevalence on farms in one intervention group declined 30% more than in the control group (Figure 1). This intervention package consisted of very dry bedding, stable groups throughout rearing, keeping a closed herd and preventing young-stock to have direct contact with other cattle. When the results were adjusted for compliance, this difference in risk reduction was statistically significant (risk ratio = 0. 14, p<0.05). The study showed that simple practices such as improved hygiene and increased biosecurity can reduce zoonotic agents, if they are applied consistently and systematically. The control measures identified in this study are common good management practices and are likely to reduce the risk of other cattle disease of economic importance. When incorporated in herd health plans, these practices will be better implemented and application sustained. The implementation is likely to result in a safer environment for the farmer, his family and staff and ultimately improve public health. Furthermore, it may provide the individual farmer with auditable evidence of action, if the need arises.