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H5 Infection in Domestic Duck on Second Abottsford Farm
Recombinomics Commentary
November 22, 2005
The infected bird was found on one of 62 farms quarantined Thursday after the first case was discovered in a domestic duck in the Fraser Valley, an agricultural swath of land stretching 100 kilometres (62 miles) east of the port city of Vancouver.
The finding of H5 in another farm duck on another farm in the Abottsford area is not a surprise. Canada had reported 24% of swabs collected from healthy wild ducks in August were positive for H5 in British Columbia. The first 7 reported ducks were positive for H5N2 (2) or H5N9 (5). Since the birds were healthy, more infections in wild birds would be expected, and transmission of H5 from the wild ducks to domestic free range ducks would be expected.
Moreover, it is expected that H5 is present on more farms in British Columbia as well as the northwest region of the United States. The infected wild birds would not stop at the US border and the high frequency of positives would be expected to cause more infections of domestic birds.
Although the initial H5 positive wild birds are said to be related to North American version and to be LPAI, recent examples of LPAI H5 and H7 become HPAI have led to culling of all domestic birds positive for H5 or H7. In fact 17 million birds in the Fraser Valley were culled last year because LPAI H7N3 became HPAI.
The reason for the high detection of H5 in wild birds in Canada remains unclear. Prior collections in Canada were primarily from Alberta, and those isolates were rarely H5. The dramatic increase in H5 detection suggests H5 infections of farm birds in Canada and the United States may be widespread, and the failure of the enhance surveillance to detect the H5 infected birds remains a cause for concern.
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