Pathogens Transmitted by Migratory Birds: Threat Perceptions to Poultry Health and Production

The role of migrating wild birds in transmitting diseases of poultry or zoonoses is a contentious issue as the researchers and naturalists stands divided regarding their capability to disperse pathogens over continents. Recently, migratory birds got world wide attention during the bird flu outbreaks, as they were found capable to disseminate the deadly H5N1 avian influenza (bird flu) virus, without themselves getting affected. However, the death of migratory birds due to H5N1, reported from Asia, has fuelled anxiety and concern over the whole issue. Apart from avian influenza, migratory birds are also thought to play role in the transmission of avian viruses like Newcastle disease virus, avian pneumovirus and duck plague virus. Similarly, bacterial pathogens like Chlamydophila psittaci and Pasteurella multocida can be transmitted to domestic poultry via migratory birds. They are also known to spread West Nile virus, equine encephalitis virus, Borrelia burgdorferi and enteropathogens like Campylobacter and Salmonella, which could affect animals as will as human beings. To prevent such etiological agents from entering poultry premises, strict biosecurity and constant surveillance are of paramount importance. Hence, in the scenario of migratory birds contributing significantly to the global spread of infectious diseases, a better understanding of their role in the disease epidemiology has to be gained by implementing superior surveillance and tracking strategies.