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Commentary
Fujian H5N2 Pseudo Surveillance In Minnesota
Recombinomics Commentary
March 28, 2015 17:30
"That's it for testing," he said. "The bottom line is that migratory waterfowl weren't there when the birds [turkeys] got infected, and the resident ones [wild birds] were negative. So in Minnesota this can't be a wild bird issue."
DNR officials said earlier they had collected 148 fecal samples from wild birds in the vicinity of the western Minnesota outbreak. Wild birds have been widely suspected of spreading H5N8 from Asia to the United States and diffusing both strains within the country, but some experts have questioned that thinking.
The above comments and associated CIDRAP headline “wild birds nixed as Minnesota H5N2 source” are unfortunate. The evidence for wild birds as the source of the three Fujian clade 2.3.4.4 serotypes (H5N8, H5N2, H5N1) is overwhelming. This clade has never been reported in North America prior to December, 2014, and an enhanced surveillance effort in the administrative Pacific Flyway has confirmed Fujian H5 in 49 wild birds.
To date only one H5 has been confirmed via routine surveillance (H5N2 in a Canada goose with neurological symptoms collected on March 16). All other confirmations (see H5N2 map) were limited to samples collected in the Pacific Flyway between December 8, 2014 and January 23, 2015, which was largely limited to wild birds killed by hunters within 24 hours of collection. This approach used fresh tracheal and cloacal swabs from previously healthy birds, which were largely ducks.
The collections were made by multiple national agencies (USDA-APHIS, USGS-NWHC, USDA-SEPRL) as well as local agencies (WA-DFW, OR-DFW, ID-DFG, WY-GFD, UC Davis).
A USGS-NWHC January 26 report on the agency data through mid-January cited collection of tracheal and cloacal swabs from over 1200 birds in the Pacific Flyway (largely from Washington) and 167 (13.9%) were influenza A positive (based on PCR positive M gene), which is a common frequency for ducks, which are infected with a wide range of influenza serotypes. The 167 influenza A positives yielded 7 that were Fujian H5 confirmed.
A recent study on H5N8 in the Netherlands tested swabs from live birds as well as “ fresh faeces” from a broard spectrum of species including ducks. Samples collected prior to reports of H5N8 included 2071 from ducks, which yielded 455 influenza A positives (22.0%), while testing after H5N8 confirmation, 2,424 ducks were tested and 264 were influenza A positives (11.0%) which yielded two H5N8 cases.
In Minnesota migrating birds were not tested because of claims of no such birds because free water was limited (in Minnesota, the “land of 10,000 lakes”). A helicopter tour (after confirmation) of the area identified resident ducks and 148 fecal samples were collected and 2 were influenza A positive (1.35%), This low frequency raises serious questions about the quality of the samples, and the likelihood of detecting Fujian H5 in 2 influenza A positive samples is very small.
Now there have been two more commercial turkey farms H5N2 confirmed in Minnesota (Lac Qui Parle and Stearns counties), signaling a profound surveillance failure linked to routine surveillance and false negatives.
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