Avian-livestock links in the demography of zoonotic bacteria and their implications for farm-worker health

Zoonotic disease occurs when humans come into close contact with the normal reservoirs or vectors of disease-causing pathogens. Farms provide multiple opportunities for exposure of workers to pathogens carried by livestock, and possibly by wildlife associated with livestock. The demography of pathogens in livestock is likely influenced by interactions with wildlife, yet little is known about the factors affecting these interactions. We propose a pilot study of disease-causing bacteria and the role of avian-livestock interactions in the demography of these bacteria in the agricultural landscape. We propose to longitudinally sample house sparrows (Passer domesticus), livestock (goats, horses, and cows), and possible transmission areas (e.g., water or feed bins) for several types of disease-causing bacteria on UK's Maine Chance Farm. The results will provide initial findings on prevalence, spatial and temporal dynamics, and possible transmission mechanisms. These pilot data will catalyze the development of more extensive studies of the role of birds in health issues facing agricultural workers, funded by the USDA, NIH, or NSF. Specific Aims 1. To document spatial and temporal patterns of disease-causing bacteria of potential risk to humans and the association between prevalence in free-living house sparrows and in three species of livestock (goats, horses, and cows). 2. To test alternative hypotheses for possible transmission between birds and livestock: a. Transmission occurs, possibly symmetrically, through joint use of water or food dispensers, indicated by contamination of bacteria present in both birds and livestock, b. Transmission occurs asymmetrically, possibly through birds foraging in and around livestock feces, and livestock though contaminated feed or water. 3. To assess bacterial demography in birds by surveying multiple age classes, sampling individuals repeatedly, and monitoring the movement of birds among locations.