| Avian influenza (AI) outbreaks in commercial poultry have significant economic, animal welfare and human health implications. Characteristics of a region, including topography, poultry rearing systems, and farm density affect AI transmission. This thesis describes our investigations of potential AI transmission pathways in Canada. We investigated wild bird and human activity on commercial poultry farms, human and poultry movements in backyard flocks, and backyard flock owners' perspectives about AI. Field data was gathered by on-farm observation and speaking directly with poultry farmers. Wild birds were counted at 41 poultry farms in British Columbia (BC) and Ontario, and the literature was reviewed to gather information about AI pathobiology in the species observed. In BC, wild bird numbers were greatest in autumn (950 birds/hr), declining through winter, then spring, to their lowest in summer (374 birds/hr), while in Ontario numbers were greatest in spring (352 birds/hr), declining through summer, then autumn, to their lowest in winter (98 birds/hr). Species active near barns were the European Starling and Rock Dove in both provinces; the Northwestern Crow, Dark-eyed Junco, and Song Sparrow in BC; and the Homed Lark and Common Grackle in Ontario. Information about AI pathobiology in most wild bird species was insufficient to estimate the risk of AI transmission to poultry posed by exposure to wild birds. Links between poultry farms generated by human activity were examined by interviewing visitors to eight commercial poultry farms in Ontario and 18 backyard flock owners in Be. At commercial farms, 43% of participants entered the poultry barns and travelled directly between farms, while 17% of backyard flock owners had frequent contact with other backyard flocks or commercial poultry. All reported poultry movements between commercial and backyard sectors were unidirectional from commercial to backyard flocks. Participants in both studies reported variable use of biosecurity practices. Backyard flock owners believed AI was a concern of commercial poultry, and disagreed with use of preemptive control practices in backyard flocks. Together, these studies suggest that human movements could act as important AI transmission pathways between commercial farms, but are less likely to transmit AI from backyard to commercial poultry. |
