The H5 avian influenza A virus that devastated North American poultry farms in 2014-15 was initially spread by migratory waterfowl, but evidence suggests such highly pathogenic flu viruses do not persist in wild birds. While wild ducks and other aquatic birds are known to be natural hosts for low pathogenic flu viruses associated with milder symptoms, the results of this study indicate that is not the case with the highly pathogenic flu viruses that are associated with more severe illness. The research suggests that wild ducks and other aquatic birds are not an ongoing source of highly pathogenic flu infection in domestic poultry. The findings provide a scientific basis for the decision by officials to use culling and quarantines to stop the 2014-15 outbreak in domestic poultry. Now, research is needed to identify the mechanism that has evolved in these wild birds to disrupt the perpetuation of highly pathogenic influenza. In this study, researchers analyzed throat swabs and other biological samples taken from 22,892 wild ducks and other aquatic birds collected before, during and after a 2014-15 H5 flu outbreak in poultry. The outbreak has been linked to a highly pathogenic H5N8 influenza A virus spread from Asia to North America by migratory waterfowl. The H5N8 virus reasserted, or mixed genes, with other influenza viruses in North American waterfowl and went on to trigger 248 flu outbreaks in commercial and backyard turkey and chicken farms in the U.S. and Canada at a cost of nearly $5 billion. http://phys.org/news/2016-07-evidence-migratory-birds-reservoir-highly.html
