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Commentary
USDA Expands Fujian H5 Surveillance To Snow
Geese In Iowa
Recombinomics Commentary
March 22, 2015 20:00
01-10-2015 Mallard Walla Walla WA 03-18-2015 USGS-NWHC
01-14-2015 Green-winged Teal Lane OR 03-18-2015 USDA-APHIS
01-17-2015 Mallard Canyon ID 03-18-2015 Idaho DFG
01-18-2015 Green-winged Teal Ada ID 03-18-2015 Idaho DFG
H5N8
12-22-2014 Mallard Bingham ID 03-18-2015 USDA-APHIS
12-22-2014 Mallard Bingham ID 03-18-2015 USDA-APHIS
01-01-2015 Northern Pintail Whatcom WA 03-18-2015 USGS-NWHC
The above lists represent the 4 H5N2 and 3 H5N8 confirmations by APHIS on March 18, which were added to the March 20 update of confirmed wild birds H5 cases. The 7 entries increased the total to 45 (16 H5N8, 28 H5N2, 1 H5N1), but did not identify any confirmations for collections outside of the Pacific Flyway or after January 23, 2015.
Two of the above collections were from 2014 (December 22 from Idaho), while the five 2015 collections were prior to January 19. These additions highlight the wild bird surveillance, which targeted wild birds in the Pacific Flyway and heavily relied on hunter killed birds, which limited testing to December, 2014 and January, 2015 since the enhanced surveillance began after H5 was confirmed in Fraser Valley in early December, and the hunting season ended in January.
After the Canadian OIE report on H5 on Decener 3, 2014 the USDA enhanced surveillance via national agencies such as APHIS and USGS, as well as state agricultural agencies. Samples collected December 8 confirmed H5N2 and H5N8 within 7 miles of Fraser Valley, which was also true for H5N1 a few weeks later (all three were in Whatcom County, Washingon.
A January 26 USGS report cited collection of over 1200 samples by USGS-NWHC which yielded 7 positives, which were present in the wild bird table prior to the latest update, which added two more, indicating only part of the collection had been tested by mid-January.
Two of the backyard farm H5N2 confirmations were in Benton County in southeast Washington, and wild bird testing identified H5N2 in a Red-tailed Hawk in Benton County, as well as 2 Mallards in the adjacent Walla Walla county. However, testing of fewer than 100 hunter killed birds in Morrow County in Oregon (about 25 miles from the backyard farms) yielded 6 positives (3 Wood Ducks and 3 Northern Sholvelers), signaling a detection frequency 10 times higher than the overall frequency for USGS-NWHC (although the frequency may rise with additional testing).
Thus, the testing in the Pacific Flyway, which largely relied on hunter killed birds, found 45 positives which included H5N2 in eight species (American Green-winged Teal, Canada Goose, Cooper’s Hawk, Mallard, Northern Pintail, Northern Shoveler, Red-tailed Hawk. Wood Duck). H5N8 was also found in eight species, including four that overlapped with H5N2 (American Green-winged Teal, Canada goose, Mallard, Northern Pintail) and four that were unique to H5N8 (American Wigeon, Bald Eagle, Gadwall, Peregrine Falcon). In addition, H5N1 was detected in an American Green-winged Teal, a species also positive for H5N8 and H5N2.
The US has a robust surveillance system in place. Each state lab can collect and H5 PCR confirm samples, which are then sent to the APHIS facility in Iowa for final confirmation. Targeting of hunter killed birds simplifies the collection procedure, which limits samples to those to birds killed less than 24 hours earlier, which are presumed to be healthy birds which can readily transmit H5.
The USDA used migration patterns that generally went north to south in the fall and south to north in the spring along four flyways which are defined by state borders. International flyways divide the Americas into three flyways with significant overlap with eashc other. Moreover, the Pacific and Mississippi flyways overlap with the East Asia – Australia flyway, allowing birds from Asia to mix with North American birds which then migrate over a large portion of the US lower 48 states. These overlapping flyways also allow for co-infections by Asian and North America influenza, which can produce reassortants like the H5N2 and H5N1 versions which all have the same Fujian clade 2.3.4.4 H5, but also have North American wild bird flu genes which produce “made in America” constellations with ratios of 5/3 and 4/4 for H5N2 and H5N1, respectively.
When H5 was reported in Fraser Valley, the USDA increased surveillance in the Pacific Flyway, defined by the four divisions in the US. However, most of the positives in Canada and the US were in the overlapping region of the Pacific and Mississippi flyways, so birds that flew into the Central and Mississippi Flyways would not be tested, leading to an absence of wild bird positives as seen for all of Canada, which also adopted a “no test = no problem” approach to wild bird surveillance.
However, the detection of H5N2 in five farms in four Midwestern states exposed the fatal flaws in the no test / no problem approach.
Although the waterfowl hunting season has ended, a season for overpopulated species like snow geese has started in many states, including Iowa, where the DNR in association with the USDA is planning on testing 150 hunter killed snow geese, which are currently migrating to Canada.
It is unclear if this program is being expanded to other states in the Midwest.
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