Qinghai H5N1 Expected in Norfolk England
Recombinomics Commentary
November 13, 2007
Geoffrey Buchanan, operations director of Redgrave Poultry, which rents the farm, said that all employees at the site had been given antiviral drugs as a precaution.
He added that all the birds on the site were now indoors,
Defra officials said that 10% of birds in one shed died over one night.
Susan Watts, science editor of the BBC's Newsnight, said that this would seem to suggest that the outbreak involved a highly pathogenic strain of the virus.
The above detail supports H5N1 infections of the turkeys at the farm at Redgrave Park near Diss in Norfolk, England. One of the hallmarks of highly pathogenic H5N1 is rapid death, which is consistent with the deaths of 10% of the population in the shed in one night. Use of anti-virals for employees is usually reserved for highly pathogenic avian influenza. Moreover, the public warnings included a description of symptoms that matched HPAI H5N1.
Wild birds are implicated because the domestic birds were free range and the farm is adjacent to a large ornamental lake (see satellite map). Moreover, the farm had not received any new birds in the past four weeks.
Although H5N1 has been reported in Great Britain previously, if confirmed this would be the first report of H5N1 in free range domestic poultry. Although the H5 infection was discovered early, the suspected linkage to wild birds raises additional surveillance issues.
Like the H7N2 infections this year, and the H7N3 infections last year, the source of these infections is likely to be infected wild birds which have not been detected by the surveillance system.
Surveillance failures were also suggested during outbreaks throughout Europe in early 2006, as well as a large outbreak in Germany during the summer of 2007, Although H5N1 was widely detected in dead or dying wild birds, it was not detected in asymptomatic wild birds.
The deaths of domestic birds in Germany led to antibody testing in farms that were commercially linked, and H5N1 antibodies were detected. These antibodies in healthy birds signaled asymptomatic infections and recovery in the absence of earlier detection.
The antibodies in asymptomatic waterfowl as well as H5N1 RNA and virus in dead or dying wild and domestic birds, raises serious questions about surveillance programs designed to detect H5N1 in domestic or wild bird populations.
The outbreak in England is likely to be linked to Qinghai H5N1, and additional outbreaks in the region are expected.
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