H5N1 in England Detected by Accident?
Recombinomics Commentary 21:27
January 14, 2008
Between 27 December and 4 January three swans were found in Abbotsbury Swannery and the vicinity in the Chesil Beach area in Dorset. Preliminary reports suggest that two of the swans were still alive when found but were euthanised due to injuries.
The above comments from the OIE report released today suggest the H5N1 found in England (see satellite map) may have literally be found by accident. If the two swans injured by accident had not be found and euthanized, there would have only been one dead swan in the period between December 27 and January 4, and the one dead swan may have not been sent for testing, or missed in the screening.
Although DEFRA asks for reports of dead birds, they frequently discourage reporting of single dead birds. The surveillance in the past has been poor, and the recent detection of H5N1 involved a single whooper swan on the shores of Scotland in 2006, as well as the more recent outbreak in free range turkeys in Suffolk. In 2006 and 2007 there were also H7N3 and H7N2 outbreaks in domestic poultry, but the wild bird sources for the three domestic poultry outbreaks were never identified.
The OIE report suggests that two of the H5N1 infected birds were asymptomatic, and it is not clear that the infection contributed to the accidental injuries. H5N1 is rarely found in live asymptomatic birds, but a recent report suggests that mute swans may be one species that sheds higher levels of the Qinghai strain of H5N1, the strain reported for all outbreaks west of China.
Recently, Germany also reported H5N1 in an asymptomatic grebe, and like both recent H5N1 outbreaks in England, the outbreak involved the Uva Lake variant of the Qinghai strain.
Finding H5N1 in asymptomatic wild birds suggests infections are widespread in Europe, as H5N1 expends its geographical reach under the radar of existing surveillance programs.
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