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Commentary
Poor Fujian H5 Surveillance Creates Wild US
Media Myths
Recombinomics Commentary
March 21, 2015 21:00
The above comments in the March 20, 2015 APHIS influenza update notes US states where at least one of the three Fujian clade 2.3.4.4 serotypes (H5N8, H5N2, H5N1) has been detected. The table in the update also includes mid-western states in the Mississippi or Central flyways (Minnesota, Missouri, Arkansas, Kansas) where H5N2 was recently confirmed (see H5N2 map).
The detections in the Midwestern states raise serious surveillance concerns.
Although the US and Canada increased wild bird surveillance in 2006, after Qinghai clade 2.2 was spread by wild birds from China (detected in the spring at Qinghai Lake) to Russia, Kazakhstan, and Mongolia in the summer, and then to 40 countries in Europe, the Middle East, Africa, and south Asia between the fall of 2005 and the spring of 2006, the surveillance efforts had not procued a confirmed case. The closest was PCR confirmed H5 in a gosling on Prince Edward Island (where 4 goslings died), but the shipment of the sample for confirmation was delayed and was degraded when it arrived at the National Labs in Winnipeg and was not confirmed.
In recent years programs in both countries were scaled back, and neither program identified the H5N2 that affected 12 farms in British Columbia (Fraser Valley) prior to the December outbreak, even though H5N8 had been reported in farms and wild birds in Europe in November, 2014 (which followed a massive outbreak in South Korea in early 2014).
However, the US increased surveillance after the Fraser Valley confirmations, and one week after the December 1 collections in Canada, the US collected samples from a wild bird that had died at Wiser Lake, 7 miles from the Canadian border, as well as a captive gyrfalcon that died after eating a wigeon collected near Wiser Lake. These samples were positive for H5N2 and H5N8, respectively. Shortly thereafter H5N1 was identified in a hunter killed wild bird near Suma, about 5 miles south of the Canadian border.
Sequences from these three isolates indicated the H5N8 had evolved from the sequences in South Korea, but was most closely related to a crane sequence from Japan, A/crane/Kagoshima/KU1/2014, (which formed a separate subclade). Co-infections in North America involving H5N8 and North American (NA) wild bird flu sequences produced H5N2, with a ratio of H5N8 to NA segments of 5 to 3, while an independent reassortment between H5N8 and another North American wild bird flu produced an H5N1 with a ratio of 4 to 4.
Thus, the sequence data indicated the parental strain (H5N8 with 8 gene segments matching the crane in Japan) arrived in North America where co-infections by flu viruses in native wild birds produced the two reassortant (H5N2 and H5N1) via independent infections. Sequences from the massive outbreak in Taiwan show similar events where an H5N8 closely related to the crane sequence in Japan acquires Asian wild bird flu virus to produce H5N8, H5N2, and H5N3 with H5N8/wild birds flu ratios of 6:2. 4:4, and 2:6.
Thus, the H5N2 and H5N1 reassortants in North America have a genetic “made in America” signature, while H5N8, H5N2, and H5N3 in Taiwan have a "made in China” genetic signature.
The Asia flu genes in the North American isolates support the transport to Alaska and northern Canada via the Eastern Asia – Australia flyway, which overlaps the Pacific and Mississippi flyways (using a simpler international representation of 3 flyways in the Americas, which combine the Mississippi and Central flyways used by the USDA). The USDA administrative system keeps each flyway separated largely by using state borders.
However, the international flyway systems shows significant overlap including those described above, as well as overlaps between Pacific and Mississippi flyways where most of the initial positives in Canada and the United States were located.
However Canada does not appear to have a viable wild bird program in place because they have yet to identify a single wild bird Fujian H5 infection. In contrast, the US has reported 45 such infections, but all are in the Pacific Flyway with collection dates in December, 2014 or January, 2015 because the vast majority of wild bird testing involves hunter killed birds in states in the Pacific Flyway, and hunting season ended in January.
Thus, the abrupt halt in wild bird confirmations in samples collected after the most recent collection (a mallard on January 23 in Nevada) and the absence of any wild bird confirmations outside of the Pacific Flyway, is due to a lack of wild bird testing and not due to a disappearance of H5 in wild birds or an absence outside of the Pacific Flyway in the United States, as was clear when H5N2 was recently confirmed in farms in Minnesota, Missouri, Arkansas, and Kansas.
These appearances do not reflect a migration from north to south or west to east (as stated in wild and nonsensical media myths), but simply reflect infections due to wild birds in the Midwest, which were not tested or reported because they were not located in the Pacific Flyway.
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