H5 Positive Geese in Canada Lead to Broader Investigation
Recombinomics Commentary
June 18, 2006
A second Prince Edward Island farm has been placed under a quarantine order as a precautionary measure as authorities investigate the finding of an H5 avian flu virus in a domestic goose in that province.
An official of the Canadian Food Inspection Agency said the move was taken when investigators learned there was traffic of people and perhaps poultry between the two farms, which both had free-range backyard flocks.
Ottawa-based Dr. Jim Clark said no birds from the second farm have displayed signs of illness and for the time being, authorities have not ordered their destruction.
Clark, who is the national manager of CFIA's avian influenza working group, said a post-mortem examination of the goose that tested positive for the H5 virus did not reveal what killed the bird.
The above comments provide additional indications that the H5 detected on a backyard farm on Prince Edward Island is the Qinghai strain of H5N1. That strain is widely circulating in long trange migratory birds and is most likely to infect free range backyard flocks because of interactions between the wild and free range domestic birds.
Although low pathogenic H5 has been reported across southern Canada last year, the H5 detected was from healthy wild birds. The H5 was in swabs from health young birds that were being banded and released. This birds did not display signs of illness.
The H5 detection has led to increased surveillance and a low path H5N2 isolate was found in a duck at a processing plant. The OIE report of November 20, 2005 indicated
The suspect bird was a 40-day-old meat duck collected at processing. The bird was in excellent body condition with submitting criteria of dermatitis. No other visible lesions and no indication of any active disease process were observed on post-mortem examination.
That report specifically indicate that the post mortem gave no indication of active disease. The above media report merely stated that the post mortem did not reveal what killed the bird. It did not indicate an infectious process was ruled out.
If the H5 was coincidental the usual walk of the birds preceding their death might have been due to poisoning. However, the latest media report did not point in that direction.
The death of four birds by low path H5 would be unusual. Most waterfowl do not show ill effects from low path, and waterfowl frequently ho no signs of infection when infected with high path H5N1.
That is why the four dead geese with symptoms prior to death strongly point toward a highly pathogenic strain, such as Qinghai H5N1 bird flu. The delay in determining the pathogenicity is also of concern. The Asian strain of H5n1 is easily characterized by sequencing the HA cleavage site. Thos test is routine and diagnostic for high path. All H5 with a cleavage site of GERRRKKR has been the highly pathogenic H5N1 and almost all have been the Qinghai strain that is in long range migratory birds.
The four dead birds began showing symptoms on June 4, and died the next day. It is now almost two weeks since symptoms were observed yet no information on the HA cleavage site has been released. The delays in characterizing the cleavage site create addition cause for concern.
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