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H5 Confirmed In Four Fraser Valley Canada Farms
Recombinomics Commentary
December 5, 2014 04:00

Harpreet Kochhar, DVM, PhD, Canada's chief veterinary officer, said in a press briefing today that test results on turkeys at a farm in Abbotsford and on chickens at a farm in Chilliwack confirmed highly pathogenic H5N2. Two other farms, also in Abbotsford and Chilliwack, that received chickens from the first Chilliwack farm have birds that tested positive for H5

 "We think that it's about a 3- to 5-day incubation period. And we also know that if it hits, the [poultry] producer isn't going to miss it."
the outbreak at the initially affected farm in Chilliwack was restricted to one of three barns. In the affected barn, all 700 of the 24-week-old chickens died from H5N2.

Pritchard said that at the Abbotsford turkey farm, the "vast majority" of 11,000 turkeys died from H5N2.

The above comments provide additional detail on the HPAI H5N2 outbreak in Fraser Valley in British Columbia (see map).  The first two farms (Abbotsford turkeys and Chilliwack chickens were not linked but developed a highly pathogenic H5N2 in the same time frame strongly suggesting infection by wild birds.  The OIE report suggested the outbreak began on November 30 and mortality was very high, as noted above and in media reports that noted significant numbers of deaths on December 1.  This time frame suggests that the infectious agent (in the wild birds) already was highly pathogenic.

Canada has never reported an HPAI H5N2 outbreak.  The three prior H5N2 outbreaks were low path and effectively managed through culling.

Both high and low path outbreaks are reportable for H5 and H7 because of reports of low path evolving into high path on infected farms.  This type of evolution happened for H7N3 in 2004.  Initial cases were low path, but over time a high path version emerged, which led to the culling of 17 million birds in Frazer Valley.

The absence of reports of an initial low path outbreak in Fraser Valley in 2014 raises concerns that high path H5N2 is circulating in wild birds. 

Although high path H5N2 has never been reported in wild birds or poultry in Canada, such isolates have been reported in Asia, including isolates with a Fujian clade 2.3.4 H5.  This H5 has been found in multiple serotypes (H5N1, H5N2, H5N5, H5N6, H5N8), raising concerns that the H5N2 in Fraser Valley is from the Asia lineage.

An Asian linage would be a significant concern, because wild birds have developed immunity to this H5, which has a lethality in poultry similar to the numbers described above.  The Fujian H5N8 has captured a great deal of attention because of recent isolates in asymptomatic wild birds in Germany (teal), Netherlands (Eurasian wigeon) and Japan (Tundra swan, ducks, white naped crane), which are lethal in domestic turkeys, chickens, and ducks (see map).

The Asian lineage has never been reported in the America, so a Fujian H5N2 would represent a serious development. 

The lineage can be easily determined through sequence analysis. 

Release of the H5 PCR insert or large pieces of the H5N2 genome would be useful.

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