AIRBORNE TRANSMISSION OF SALMONELLA AND ITS ASSOCIATION WITH DUST IN POULTRY HOUSES
Type of DegreeMaster's Thesis
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Poultry house dust has been reported to contain pathogenic bacteria. Previously, the presence of Salmonella has been observed in airborne and settled dust in poultry houses. Therefore, it is important to investigate the sources of dust contamination with Salmonella in poultry houses and the likelihood of Salmonella colonization in chickens through airborne dust. We conducted three studies with objectives to explore the role of litter properties in transfer of Salmonella from litter to dust, the changes in Salmonella prevalence in dust deposited at different surfaces during broiler growout, and the likelihood of Salmonella colonization in broilers through Salmonella contaminated aerosol. Briefly, to accomplish these objectives, an in vitro setup was designed to assess the role of litter Salmonella and moisture levels in transfer of Salmonella from litter to dust, dust samples were collected from two broiler flocks (Flocks A and B), where birds in Flock B were inoculated with S. Enteritidis, to analyze the changes of Salmonella prevalence in dust during growout, and day-old broilers were exposed to S. Enteritidis aerosol to analyze Salmonella colonization in ceca, trachea, and liver/spleen over time. We observed that increasing litter Salmonella (10^2 to 10^9 CFU/mL) levels led to increased occurrence of Salmonella positive dust and increasing moisture (12.1 to 34.8%) levels decreased the occurrence of Salmonella in subsequent dust samples. Our second study reported the presence of Salmonella in dust deposited at different surfaces, however; Salmonella prevalence did not vary in cumulatively and non-cumulatively settled dust during growout in both Flocks A and B. In our last study, we observed Salmonella colonization and persistence in different tissues of broilers after exposure to different levels of Salmonella aerosol. Overall, Salmonella presence in poultry house dust and the potential risk of high levels of airborne Salmonella to poultry has been confirmed.