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Toronto Requests Dead Wild Birds For H5N1 Tests
November 30, 2006
Torontonians are being asked to keep an eye out for dead birds.
The province is taking part in a national project involving dead birds. This project will help Ontario address the risk of avian influenza.
Canada is monitoring the many strains of avian influenza that naturally occur in wild bird populations. One way this is tracked is through the collection and testing of dead birds. This method is only successful if there is a significant level of public participation and awareness.
The above request, made today, is better late than never. To date, most surveillance for H5N1 in wild birds in Canada has focused on live birds. However, H5N1 is almost always initially detected in dead birds, wild or poultry. Detection of H5N1 in live birds is generally limited to locations where H5N1 had been previously found in dead birds.
In the United States, over 35,000 live or hunter killed birds have been tested. H5N1 has been detected, and on rare occasions has been isolated. However, there are no listings of H5N1 found in dead or dying birds. Reported low path H5N1 has been reported in the absence of high path. However, the failure to find any H5N1 in dead birds signals an experimental design flaw.
Unfortunately, this fatally flawed approach is not unexpected. In Africa, 15,000 live wild birds were tested by conservation groups and no H5N1 positives were reported. However, H5N1 is widespread in Africa. It has been detected in dead poultry in Egypt, Sudan, Nigeria, Niger, Ivory Coast, Burkino Faso. In all cases the Qinghai strain was detected, and the sequence data showed that the isolates were from independent introductions, indicating they were from wild birds.
Thus, channeling surveillance resources into live bird testing is a formula for failure, which is clear from the data presented in the United States and Canada.
Canada however did find H5 in a dead farm goose. Four geese died suddenly after displaying H5N1 symptoms. Only one was tested and H5 was confirmed with a PCR test, but the size of the insert was withheld.. After a week on Prince Edward Island, the sample was shipped to Winnipeg for confirmation of the confirmation, but by then the sample had degraded and the confirmed results in PEI was not re-confirmed in Winnipeg. As a result, Canada did not file file the mandatory OIE report. H5 in farm birds generally leads to import bans, which were avoided by simply failing to confirm the data.
That confirmation failure was followed by an unusually high level of detection of influenza in live and dead birds on PEI this year. However, the number of dead birds tested has been low.
Similarly, H5N1 has been detected at several locations in the Great Lakes region. Although there have been massive die-offs of wild birds in the same areas, there are no dead birds that were positive from low or high path H5N1, which is clearly due to a lack of testing.
The increased effort announced above may yield a sufficient number of birds to more accurately represent the level of low and high path H5N1 in the area.
Similar requests should be made throughout North America.