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It is recognized that Campylobacter jejuni and Salmonella are two pathogens commonly found in commercially reared poultry and they are both associated with food borne illness in humans (Oyofo et al., 1989; Mulder, 1995; Gast, 1997; Shane, 1997). Due to these facts, government officials are currently discussing whether or not Hazard Analysis and Critical Control Point (HACCP) type programs need to be implemented on the farm, like those already in place for post-harvest facilities (USDA, FSIS, 2008). The proposed regulations by the Food Safety Inspection Service (FSIS) would target the site where primary microbial infection of poultry occurs, to potentially reduce the microbial load entering the processing facility. Thus, scientific based research must be conducted to determine what regulations would be most effective on the farm. Dr. Merle Pierson, the Acting under Secretary for Food Safety in 2005 stated, "The Office of Food Safety has used science-based policies to effectively protect the health and well being of millions of consumers worldwide". Dr. Pierson also states in his speech that although implemented regulations have driven down Salmonella, E. coli O157:H7 and Listeria monocytogenes prevalence rates, there is still important work ahead in addressing Campylobacter. Therefore, the goal of the following research projects will be focused towards understanding the interactions Campylobacter and Salmonella have with poultry in an attempt to develop strategies that will reduce their presence on the farm.
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The goals of this CRIS will ultimately be obtained through a series of 4 projects. The objective of the first project will be to obtain information on the level of Campylobacter and Salmonella harbored in modern commercial poultry facilities during grow out. The results will be collected through on farm surveys and will be used as a model to establish areas of focus for future research efforts. The objective of the second project will be to investigate the effectiveness of different composting practices on litter in an attempt to reduce the levels of Campylobacter and Salmonella. The objective for the third project will be to investigate the potential of vertical transmission as a route of colonization in young poultry flocks by using bioluminescent phenotypes of Campylobacter and Salmonella. The fourth project will investigate whether or not vaccines can be developed and effectively used to prevent colonization of poultry flocks by Campylobacter and Salmonella.
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The projects outlined in this CRIS proposal will provide results for the poultry industry that will allow them to identify sources of contamination on the farm and implement safety practices to correct them. It will also provide new data and strategies for government officials to use in making critical decisions concerning regulatory interventions focused on reducing the prevalence rates of pathogens on the farm. Most importantly, the largest impact of this research will be taking steps to ensure the safety of consumers 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. Out of the 76 million cases, 325,000 result in hospitalization and 5000 are fatal (WHO, 2007). The financial burden that the former have placed on the United States is staggering. It is estimated that illnesses caused by contaminated food cost the United States approximately 44 billion annually, due not only to medical costs but also losses in productivity (Trust for Americans Health, 2008). 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). Poultry has been found to be a major reservoir for both Campylobacter and Salmonella (Oyofo et al., 1989; Gast et al., 1997). This is a concern for government officials as well as to the poultry industry, since poultry consumption has continued to increase over the past several years. In 2006, the ERS released statistical data that demonstrated that the consumption of poultry doubled between 1970 and 2004, 27.4 lbs to 59.2 lbs per capita respectively. 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 pathogen levels in a commercial facility can be taken into consideration. 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. 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.
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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 survey. After the preliminary data has been analyzed, other variables important to the survey will be identified and the survey will begin. Samples will include environmental and historical data as well as microbiological samples. These results will provide scientists with a pathogen map, a model for calculating the level of contamination, as well as method for identifying patterns of pathogens proliferation. The second study will use, used litter from the MSU commercial broiler houses that has been decaked and split into 16 plots. Each plot will be randomly assigned one of four treatments. Treatments include: a negative control (not windrowed), a positive control (windrowed), litter contains 25% moisture and windrowed, and litter that contains 30% moisture and windrowed. The house will pasteurize 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 ratio, and ammonia flux. 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 yield, 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 for horizontal transmission. The goal the third study 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. Roosters 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 the luminescent bacteria. The results from these experiments have potential to provide information confirming or denying vertical transmission. In the fourth study male and female broiler chickens from a commercial broiler flock will be selected for carrying high or low levels of Campylobacter. Those individual birds will be subjected to brachial vein puncture and proteins from the blood will be separated using 2-D gel electrophoresis. Over expressed proteins will be excised from the gel and sent to the Life Science and Biotechnology Institute 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.