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Thursday 24th May 2018

Wild ducks may spread bird flu

10th November 2008

New scientific research has found that wild migratory birds may be more important carriers of avian influenza viruses from continent to continent than previously thought.


In a multi-pronged research effort to understand the role of migratory birds in the transfer of avian influenza viruses between Asia and North America, researchers found evidence that the virus may be carried accross continents by wild ducks; specifically the northern pintail.

The findings have important implications for highly pathogenic avian influenza virus surveillance in North America, according to scientists with the US Geological Survey (USGS), the US Fish and Wildlife Service in Alaska and the University of Tokyo.

Almost 50% of the low pathogenic avian influenza viruses found in wild northern pintail ducks in Alaska contained at least one of eight gene segments that were more closely related to Asian than to North American strains of avian influenza.

However, none of the samples contained completely Asian-origin viruses and none were highly pathogenic forms that have caused deaths of domestic poultry and humans.

Study co-author Chris Franson, a research wildlife biologist with the USGS National Wildlife Health Centre said the findings, published in the journal Molecular Ecology, challenged current assumptions that transmission through migrating birds was rare.

The role of migratory birds in the global spread of the highly pathogenic H5N1 bird flu virus is still the subject of fierce debate in the scientific community.

Previous studies examined bird species that are not transcontinental migrants or were from mid-latitude locales in North America, regions far removed from sources of Asian strains of avian influenza, Franson added.

Samples were obtained from more than 1,400 northern pintails from locations throughout Alaska, with the help of local scientists and native communities.  

Those containing viruses were compared to virus samples taken from other birds in North America and Eastern Asia where northern pintails - a common species in both North America and East Asia - are known to winter.  

Researchers chose northern pintails as the focus of the study because they are fairly common in North America and Asia, they are frequently infected by low pathogenic avian influenza, and they are known to migrate between North America and Asia.

Co-author John Pearce, a USGS research wildlife biologist in Alaska said the research validated our current surveillance sampling process for highly pathogenic avian influenza in Alaska. It also showed that genetic analysis was an effective tool in the surveillance of pathogens.


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