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H5N1 Bird Flu in North America?
February 19, 2006
59 samples from several species, including whooper (_Cygnus cygnus_) and mute swans (_Cygnus olor_), Canada geese (_Branta canadensis_), tufted ducks (_Aythya fuligula_) and a hawk (_Accipiter gentilis_).
Excessive viral loads indicated highly acute systemic infection. Sequencing of the HA proteolytical cleavage site showed a polybasic pattern (SPQGERRRKKR*GLF) indicative of highly pathogenic properties. Limited phylogenetic analysis of a 600 nt fragment of the HA gene revealed closest relationship with recent isolates from Romania, and, more distantly, with sequences from whooper swans of Lake Erkhul, Mongolia.
All positive cases are restricted to the island of Ruegen, where large numbers of migratory birds are wintering.
The above comments provide additional support for significant levels of the Qinghai strain of H5N1 in western Europe. The above list is limited to dead birds on Germany's Ruegen Island. Prior studies, including the OIE Mission Report indicated about two dozen species shot out of the sky in southern Siberia, carried H5N1 asymptomatically. These data, couple with the widespread detection of H5N1 in dead birds throughout western Europe suggest H5N1 was present in northern Siberia in the summer of 2005 and migrated to western Europe in the fall.
The number of reported die-offs were large (see December map), yet none of the EU countries detected H5N1 until very recently (see February map). Many reported Newcastle disease outbreaks, which are frequently cited in countries that subsequently become H5N1 positive. This linkage goes back to H5N1 in Indonesia and China in 2003 and 2004 and continues to the present. Many countries in the Middle East have also reported recent Newcastle Disease outbreaks, as has India.
The failure of these countries to detect H5N1 is cause for concern. The widespread reporting of H5N1 in Europe, the Middle East, Africa, and India suggest surveillance in all of the recently reporting countries is poor. However, reporting in neighboring countries that have yet to confirm H5N1 is beyond poor.
The surveillance shortcomings likely extend to North America. If H5N1 was present in northern Siberia in the summer, it was probably also present in North America because of the connection via the East Atlantic Flyway. Canada did widespread testing on young ducks capture in August of 2005. The ducks were swabbed as part of the banding experiments and H5 was detected in all reporting Provinces. Although H%N1, H5N2, H5N3, and H5N9 were detected, all reported characterizations were of LPAI.
Since the collection were limit to young ducks in the south in August, H5N1 positive birds in the north may have been missed. However, these birds in the north as well as those banded in the south should have migrated into the United States as the temperature in Canada dropped, yet the United States has not reported H5 this season. These negative data raise serious questions about the surveillance systems in North America.
As the H5N1 positive birds in the East Atlantic Fly migrate north in the upcoming months, they will once again head for western Europe and eastern North America.
An evaluation of detection and reporting in western Europe and North America would be useful.