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Our long-term objective is to carry out epidemiologic risk analysis for food- and waterborne pathogens in watersheds, at the pre-harvest level, so that cost-effective risk management strategies can be devised and adopted. The focus of the proposed studies will be on identifying on-farm sources, incidence, and associated factors of Campylobacter jejuni and Escherichia coli in dairy farms. <P>
Specific aims are: <OL> <LI> Determine the incidence of C. jejuni and E. coli in dairy herds in the Susquehanna Watershed. <LI> Identify agent, host, and environmental factors associated with the likelihood of introduction and perpetuation of these food borne pathogens.<LI> Integrate our findings into extension and educational programs for the purpose of closing the knowledge gap in mitigating the risk associated with C. jejuni and E. coli.</oL>
We are planning to carry out a combination of epidemiologic and molecular studies to address the objectives. Using a repeated cross-sectional study and a systematic sampling approach we will collect samples from dairy animals and the environment in the Susquehanna Watershed. These samples will be analyzed for the presence of E. coli O157:H7 and C. jejuni using a polymerase chain reaction (PCR) based detection system. The system consists of a combination of bacterial culturing and PCR detection. The occurrence of these two organisms in these samples will be computed. A questionnaire will be completed to identify management practices and factors hypothesized to be associated with the occurrence, introduction, and perpetuation of these water- and food borne pathogens. Using longitudinal data analysis and hierarchical model approach we will identify factors associate with the presence of these organisms and develop risk models for each. Using a combination of deterministic and stochastic approaches, scenario path models will be developed describing the transportation of these pathogenes from the source(s) to the agricultural and crop fields. The proposed research activities will generate a substantially improved understanding of the process of microbial risk of C. jejuni and E. coli from dairy farms. In conjunction with agricultural extension and regulatory stakeholders, we will develop beneficial management practices that are both science-based and supported by critical cost-benefit analyses.<P>Outcomes from the proposed studies include: 1) Advances in our understanding of the epidemiology and ecology of food- and waterborne pathogens at the pre-harvest level. 2) Provides the necessary information regarding the risk and the factors associated with the perpetuation of these pathogens in dairy farms. 3) Furthermore, and in case that we did not find these pathogens in the target population, we will be able to ascertain the safety of the food from these sources and alleviate the public concerns about the potential hazard. 4) We will identify critical control points and assess the cost-effectiveness of different interventions on the risk of food contamination. The results will be shared with other stakeholders through the extension activities.
NON-TECHNICAL SUMMARY: Food borne illness has been identified as one of the major hindrances to the advancement of health in the United States. The Centers for Disease Control and Prevention (CDC) estimates that food borne diseases cause approximately 76 million illnesses, 325,000 hospitalizations, and 5,000 deaths in the United States each year. E. coli O157:H7 and C. jejuni top the list of the causative pathogens. The reported annual incidence of these pathogens in the U.S. population was estimated at 1% with a case-fatality of 25 per million. Furthermore, food borne illnesses have become an economic burden to society with an annual cost estimated in the U.S. at $5 to $6 billion in direct medical expenditures and lost productivity. The Economic Research Services (ERS), USDA, estimated the direct annual cost of medical conditions associated with these two pathogens at $ 2.2 Billion, which is one third of the total cost. Studies that contribute to identifying the sources, incidence, and the factors associated with their introduction and perpetuation among animal populations will contribute significantly to the control and management of the associated losses. For the last year we have been carrying out epidemiologic studies to investigate the risk of Cryptosporidium and Salmonella spp. among dairy herds in this target population. Samples are been collected from the target population and examined for these pathogens. Since the major costs in any epidemiologic studies are associated with samples' collection we believe that integrating the proposed studies into our ongoing investigation will significantly reduce the cost and maximize the returns to our research. The specific expected outcomes from the proposed studies include: 1) Advances in our understanding of the epidemiology and ecology of food- and waterborne pathogens at the pre-harvest level which will help in the design of cost effective strategies to mitigate associated risk. 2) Provides the necessary information regarding the risk and the factors associated with the perpetuation of these pathogens in dairy farms. This information will be useful to farmers to identify critical control points and device a biosecurity system that will lead to the production of food with minimum pathogen load. 3) Furthermore, and in case that we did not find these pathogens in the target population, we will be able to ascertain the safety of the food from these sources and alleviate the public concerns about the potential hazard. 4) Combining the scenario path model and decision analysis approaches we will identify critical control points and assess the cost-effectiveness of different interventions on the risk of food contamination. The results will be shared with other stakeholders through the extension activities.<P>APPROACH: We are planning to carry out a longitudinal study to determine the incidence of these two food borne pathogens in the target population. Animals and environmental samples will be collected quarterly from the target population and analyzed for the presences of E. coli (O157:H7 and O157:NM) and Campylobacter spp. (C. jejuni, C. coli, and C. lari). The samples will be analyzed for the presence of these pathogens using a polymerase chain reaction (PCR) based detection system. The system consists of a combination of bacterial culturing and PCR detection. In addition, we are planning to test samples that have been collected over the past year and stored in Brain Heart Infusion (BHI) broth with 5% glycerol. The incidence of these organisms in the respective samples will be computed as the proportion of the new samples that tested positive out of all the samples examined at that specific period of time. Our overall approach can be classified as a population-based follow-up study where samples are collected (prospectively and retrospectively) randomly from a subset of animals and their environment in the target population in a previous longitudinal study. The prospective components consist of samples that will be collected during the requested funding period of this grant. The retrospective component consists of testing of the samples that have been collected during the past year through a different funding source. There will be an overlap of a year and a half between the two grants which will reduce the cost of sampling in this current funding period. As part of the problem formulation and analysis, we will collect data on factors hypothesized to be associated with the risk of these pathogens in the watershed ecosystem. Using logistic regression and hierarchical model approach we will identify factors that significantly exacerbate or modify the risk of introduction, transmission, and fade of these pathogens and develop risk models for each. The statistical analysis approach will allow us to assess the likelihood of pathogen in a particular set of samples given a specific factor while adjusting for the presence of other factors and the potential clustering of the results by farm. Such knowledge is essential for the design of cost-effective intervention strategies to control and mitigate the potential threat to the water supply systems. The expected outcomes from the proposed studies include: 1) Advances in our understanding of the epidemiology and ecology of food- and waterborne pathogens at the pre-harvest level. 2) Provides the necessary information regarding the risk and the factors associated with the perpetuation of these pathogens in dairy farms. 3) Furthermore, and in case that we did not find these pathogens in the target population, we will be able to ascertain the safety of the food from these sources and alleviate the public concerns about the potential hazard. 4) Through decision analysis approach we will identify critical control points and assess the cost-effectiveness of different interventions on the risk of food contamination. The results will be shared with other stakeholders through the extension activities.