No evidence of H5 avian influenza virus strains has yet been found by the Canadian wild bird surveillance programme aimed at detecting whether the virus has spread to Canada via migratory birds.
Testing has been completed on about a quarter of the target 12,000 birds, with no evidence of H5 avian flu viruses of any sort, according to Dr Ted Leighton, executive director of the Canadian Co-operative Wildlife Health Centre.
Leighton said more than 5000 birds have been sampled so far this year and initial tests looking for avian flu viruses have been run on about 43 per cent of those. A number of avian flu viruses have been found, but none were H5 or H7 viruses.
A similar programme in the United States has also failed to turn up any sign of the highly pathogenic Asian form of the H5N1 virus so far. This supports the contention of a soon-to-be published journal article that suggests migratory birds are an unlikely source of introduction of the virus into North America.
“It seems to me that migratory birds are extremely unlikely,” said John Rappole, an ornithologist with the Smithsonian Institute in Washington who co-authored the article, which will appear in October’s issue of Emerging Infectious Diseases.
“I certainly wouldn’t predict that it would be here this year, next year, the following year.”
So far this year the Canadian surveillance programme has focused largely on sampling of gulls, sandpipers, terns, urban geese and other non-duck species. While some samples have been collected from ducks, the major work on these types of waterfowl – believed to be the natural host for avian influenza viruses – will be done over the coming weeks as they migrate south.