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In 2007, the Trust for America's Heath conducted a public opinion poll that indicated over 67% of Americans are concerned about the safety of our nation's food supply (TFAH, 2008). This concern is most likely a result of the outbreaks that have occurred due to contaminated produce, beef and most recently peanut products. To regain public trust in the nations food supply, research focused on reducing contaminated food products is needed. <P>
Campylobacter, the leading cause of food-borne illness in the United States causes more infections than Salmonella and Shigella combined (FDA, 2007). The organism is responsible for infecting approximately 2.4 million people annually (CDC 2008), and is estimated to cost the United States, approximately 1.2 billion dollars annually (Crutchfield SR and Roberts T., 2000). This organism is associated with domestic species such as cattle, sheep, and poultry, but it is also known to be prevalent in wild birds, marine mammals, and aquatic environments (Stoddard, et al., 2005; Wilson, et al., 2005; Goldman, et al., 2008). Although the potential for a Campylobacter outbreak by any one of these many sources is high, the major reservoir of this pathogen is considered to be poultry (Oyofo et al., 1989; Gast et al., 1997). Therefore the goal of the following research projects will be focused towards understanding the interaction Campylobacter and Salmonella have with poultry in an attempt to develop strategies that will reduce their presence on the farm. <P> The first objective will be to survey commercial broiler farms to determine the amount of Campylobacter and Salmonella that are present during a typical broiler grow-out cycle. The results from these surveys will allow a model to be developed that demonstrates the distribution of these pathogens on the farm and allow for target areas for reduction to be established. <P>The second objective will include experiments aimed towards reducing Campylobacter and Salmonella in the broiler house by investigating in-house composting techniques as well as applying litter amendments to the identified target areas. <P> The third objective will include experiments aimed at understanding the role vertical transmission plays in colonizing broiler flocks using bioluminescent phenotypes of Campylobacter and Salmonella. <P>The fourth objective will include experiments directed towards the development of vaccines to immunize poultry against Campylobacter and Salmonella colonization. <P>The objectives listed in the CRIS proposal will provide results for the poultry industry that will allow them to identify sources of contamination on the farm and implement saftery practices to prevent colonization of their flocks in the future. It will also provide new data and strategies for government officials to use in making critical decisions concerning regulatory interventions focused on reducing the prevelance of food born pathogens in our food chain. Most importantly, this research will be taking steps to ensure the safety of the consumer and maintain the excellent reputation already held by the poultry industry.
NON-TECHNICAL SUMMARY: Each year in America approximately 76 million people become sick due to a food borne illness. Campylobacter jejuni is recognized by the Center of Disease Control and Prevention as the leading cause of food borne illness in the United States and it is closely followed by Salmonella (CDC, 2008a; CDC, 2008b). The cost associated with these illnesses totaled approximately 3.6 billion dollars (ERS, 2000). Poultry has been found to be a major reservoir for both Campylobacter and Salmonella (Oyofo et al., 1989; Gast et al., 1997). It is of utmost importance to keep poultry products safe and maintain the high degree of product safety since faith in the safety of our nations food supply is being questioned by the public. In 2007, a public opinion poll conducted by the Trust for America's Health indicated that over 67% of Americans are concerned about food safety (TFAH, 2008). Although the Food Safety Inspection Service (FSIS) enforces Hazard Analysis and Critical Control Point (HACCP) regulatory guidelines on poultry processing facilities (USDA, FSIS, 2008) it may not be enough. There has been discussion among government officials for the development of HACCP-type regulations for the farm. To effectively reduce pathogens on the farm, it is essential to first gain a knowledge base so that pre-existing levels of pathogens in poultry facilities can be better understood and managed. This makes an epidemiological survey of utmost importance, so that pre-existing levels in a commercial facility can be taken into consideration to extend future research that develops methods for reducing the levels of pathogens. Strategies to reduce on farm levels of Campylobacter and Salmonella can be addressed in several different ways. One area that is controversial, but needs further investigation, is the role vertical transmission has on flock contamination. If this method of transmission can be confirmed, steps toward preventing it can be studied. Another area of investigation will focus on improving the quality of litter on which young birds are placed. To investigate this, new techniques are needed that disrupt the optimum environmental conditions required for pathogens to multiply while maintaining the integrity of the litter for future flocks. It may also be advantageous to build upon previous research that has evaluated different treatments of the litter, such as chemical manipulation or pasteurization. Also, there is potential in the development of vaccines that could target specific pathogens and prevent colonization in the birds. The projects proposed in this CRIS will not only address the current levels of Campylobacter and Salmonella contamination in modern poultry farms, but also provide information to farmers on potential strategies that they may use to decrease that level of contamination. <P>
APPROACH: The first study includes the development of a pathogen map for Campylobacter and Salmonella. This map will help establish the number of samples needed to be collected for the surveys of commercial broiler houses. Samples will include environmental and historical data as well as microbioligical samples. These results will provide scientists with a pathogen map, a model for calculating the level of contamination, as well as a method for identifying patterns of pathogen proliferation. The second study will use, used litter from the MSU commercial broiler houses tthat has been decaked and split into 16 plots. Each plot will be randomly assigned one of four treatments. Treatments will include; a negative control (not windrowed), a positive control (windrowed), litter that contains 25% moisture and windrowed, and litter that contains 30% moisture and windrowed. The house will compost for 8 days. Samples will be collected 4 times; before decaking, two days after breakdown, the day chicks arrive, and seven days after placement. On sample days, litter will be analyzed for Campylobacter, Salmonella, total aerobes, total anaerobes, coliforms, pH, temperature, moisture, carbon/nitrogen, and ammonia. To evaluate whether pasteurization has an effect on production, 16 pens with 25 chicks per pen will be grown for 42 days. Data will include initial body weight, final body weight, carcass yeild, feed consumption, feed conversion, mortality, breast yield, and foot pad scores. The results from these experiments will help identify sources of disease, provide new management strategies, increase production and reduce the potential of horizontal transmission. The goal of the third objective will be to collect reproductive organs from breeding roosters and breeding hens to evaluate the attachment properties of luminescent bacteria as well as the bacteria's ability to survive in that type of environment. After the in vitro experiments, in vivo experiments will follow. Rooster's and hens at breeding age will be artificially inseminated with contaminated semen. Over specific time periods, hens will be euthanized and the reproductive tracts will be removed and observed to determine the migration of bacteria. Eventually contaminated eggs will be hatched and the offspring will be sampled for luminescent bacteria. The results from these experiments have potential to provide information confirming or denying vertical transmission. The fourth objective will use male and female broiler chickens from a commercial broiler flock will be selected and tested to determine whether or not they are high or low carrier's of Campylobacter and Salmonella. Those individual birds will be subjected to brachial vein puncture and proteins from the collected blood will be seperated using 2-D gel electrophoresis. Over expressed proteins will be excised from the gel and sent to the life science and biotechnology institute at MSU for sequencing. The results from this experiment may provide scientists with the identity of unique proteins that can be used in future research projects to develop vaccines against Campylobacter and Salmonella.