Fujian H5 In Woodstock Ontario In Atlantic Flyway
Recombinomics Commentary
April 8, 2015 03:30

The above map of worldwide migratory bird flyways (from Wetlands International) highlights the concerns linked to the recent report of H5 near Woodstock, Ontario, which is located in the above Atlantic Americas Flyway.. 

Although the full serotype is unknown, yesterday’s CFIA presser indicated the index farm had 4 barns and all symptomatic turkeys were in a flock of 12,000 which were housed in 1 barn.  The death of 7500 turkeys indicates the H5 is HPAI Fujian clade 2.3.4.4 and is likely H5N2 based on the reports of widespread  infections of that serotype (see H5N2 map) in the Midwest (in the Mississippi Flyway depicted above).

The number of recent H5N2 confirmed turkey farms in Minnesota has increased to eight.  All were commercial farms with 3-5 barns and in 7 of the 8 the symptomatic turkeys were limited to the index barn, signaling biosecurity levels that effectively limited spread but did not prevent entry to the index farm.  This pattern is similar to the first commercial farm in the US infected with Fujian H5.  The farm was in Stanislaus County, California and had 14 barns (see zoomed H5N8 map), but symptoms and deaths were limited to the index barn in spite of the close proximity of the other 13 barns.Similarly, the repeated infection of farms in Minnesota is similar to the outbreaks in Fraser Valley in December, 2014 where H5N2 infected 11 commercial farms over a period of several weeks. 

The Fraser Valley outbreak led to enhanced surveillance in the US, where H5N2 and H5N8 were quickly identified in wild birds in Whatcom County, Washington less than 7 miles from Fraser Valley.  The enhanced surveillance in the US targeted the administrative Pacific Flyway which identified H5 (H5N2, H5N8, H5N1) in 49 wild birds, which largely relied on swabs from hunter killed birds.  There have been no confirmations in the Pacific Flyway in samples collected after January 23, when hunting season ended.

The absence of enhanced surveillance also led to a failure to detect any Fujian H5 outside of the Pacific Flyway until the first farm in Minnesota was confirmed on March 4.  Two wild birds (Canada geese) were confirmed in Laramie County, Wyoming and Lyons County. Missouri through routine surveillance (testing dead or dying wild birds) as well as captive falcons who ate wild birds in Montana or Missouri signaling the spread of H5N2 outside of the administrative Pacific Flyway.The above flyway map divides North America into three flyways, which incluse significant overlap between adjacent flyways.  Most of the H5 confirmations in the administrative Pacific Flyway were in the overlapping area between the Pacific and Mississippi Flyway, and the recent cases in the Midwest are in the overlapping region between the Mississippi and Atlantic Flyway.

However, Woodstock, Ontario is located east of the overlap and is exclusively in the Atlantic Flyway and at a significant distance from H5N2 confirmations in Minnesota and Missouri, once again signaling a surveillance failure and the confirmation of H5 in a turkey farm prior to reports in wild birds in the area.

The absence of any enhanced surveillance in the United States and Canada is a concern.  Canada has yet to report Fujian H5 in any wild bird in spite of reports of H5N2 in 12 farms in Fraser Valley as well as H5N1 in one backyard farm and the H5 in Woodstock.  Similarly, the US has not reported any cases in Pacific Flyway collections after the end of hunting season, and wild bird reports in the Midwest has been limited to dead or dying birds self. 

Iowa has announced to test 150 hunter killed snow geese shot during the spring season, and other states may be following suit, but the number of planned tests is markedly below the enhanced testing in December and January in the west.  There are also plans to test fecal samples, but initial testing in Minnesota resulted in a very low frequency of influenza A positives, suggesting degradation in samples.

Robust wild bird surveillance by the US and Canada outside of the Pacific Flyway is long overdue.

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