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<p>The work consists of integrated field, laboratory and modelling studies to investigate the role of broiler systems, and bird health and welfare on Campylobacter colonisation. This will help identify intervention strategies that can be used in the industry to reduce human health risks. The work plan is split into five areas:</p>
<p><b>Historical Data:</b> Data from commercial producers on flock performance, condemnation and flock health will be collected to analyse special-temporal patterns of disease across farms and production cycles. The results form the basis for more detailed longitudinal field experiments.</p>
<b>Field Research:</b> The temporal dynamics of Campylobacter colonisation and its extra-intestinal spread will be investigated allowing the quantification of the effects of bird welfare, endemic disease and in-house environment of the bacteria. Three fundamental hypotheses will be investigated:
<ul><li>Broiler production systems and the environment they are kept affects bird welfare, which in turn determines the susceptibility of birds to Campylobacter colonisation.</li>
<li>Broiler production systems influence the impact of endemic disease, which in turn impacts on the colonisation and extra-intestinal spread of Campylobacter in birds.</li>
<li>Bird growth rate in different broiler genotypes is more important than underlying genotype in determining susceptibility to Campylobacter and endemic disease.</li></ul>
<p>Outputs from this part of the study will provide parameter estimates for the modelling of interventions to reduce Campylobacter and APEC infection.</p>
<b>Laboratory studies:</b> Studies will be performed to investigate whether infection with APEC increases a bird's susceptibility to Campylobacter and that this duel infection leads to extra-intestinal spread. Work will investigate four hypotheses:
<ul><li>Campylobacter colonises the gut of rapidly growing birds more easily than those growing more slowly.</li>
<li>APEC colonises the gut of rapidly growing birds more easily than those growing more slowly and is more likely to spread from the gut.</li>
<li>In vivo behaviour of Campylobacter will differ in birds that are also infected with APEC.</li>
<li>In birds infected with APEC, Campylobacter colonises with a lower infectious dose.</li></ul>
<p><b>Statistical modelling:</b> Data obtained from the studies will be used to identify risk factors for Campylobacter colonisation and extra-intestinal spread. Mixed effect modelling will be used to quantify the dynamics of colonisation and spread, the addition of event modelling will allow the identification of risk factors, and finally structural equation modelling will analyse the role of indirect and direct drivers in these processes.</p>
<p><b>Process-based epidemiological models:</b> Epidemiological models will be developed to identify practical options to mitigate Campylobacter infection and extra intestinal spread in production. The dynamics of changes in immunology, gut pathology and the presence in different body tissues, namely caecum and liver, will be quantified. The output from this will be used to parameterise further process-based modelling. This will enable the investigation of different intervention strategies for minimising colonisation and spread of Campylobacter. </p>
<p>Background: This project will provide the FSA, food retailers and the UK poultry industry with a series of options, aimed at reducing the number of chickens found positive for Campylobacter. This will ensure that the FSA is not only able to reduce the risk to human health from Campylobacter but also meet future EU targets aimed at reducing the number of Campylobacter positive chickens. The study will focus on intensively reared chicken which comprises approximately 90% of the UK market, and investigate the major routes of contamination including carcass surface cross-contamination and potential infectivity from the muscle and liver of chickens.</p>
<p>The study will also include field studies and investigate whether the environment in which chickens are bred affects the incidence of Campylobacter. This will be related to the health and welfare of the birds. Different intensive systems will be studied and reasons for the observed differences in Campylobacter status investigated, combined with modelling and molecular approach will be used to investigate factors that improve resistance to Campylobacter, reduce risk of colonisation and the intra-intestinal spread in UK broilers.</p>
<p>The implications of these results will be discussed in terms of reducing human health risk and the incidence of Campylobacter by modellers, microbiologists, molecular biologists, retailers and poultry producers. </p>