Multi-focal Detection of Qinghai H5N1 in Western Europe
Recombinomics Commentary
June 26, 2007
Germany identified three more cases of the lethal H5N1 strain of bird flu in swans on Tuesday, bringing the total number of wild birds infected to nine, but authorities said they had not changed their risk assessment.
The Friedrich Loeffler animal disease institute said the three swans were found near Leipzig in the eastern state of Saxony. Nine wild birds -- eight swans and a Canada goose -- had now been confirmed as H5N1 cases, it added.
"The new cases from Saxony do not change anything yet in our risk assessment," Thomas Mettenleiter, president of the institute, said in a statement.
The above comments increase the number of confirmed H5N1 infections near Leipzig and highlight the multi-focal nature of the H5N1 outbreaks in Germany and The Czech Republic. A map of the confirmed cases in OIE reports from the Czech Republic and Germany is here. These confirmed cases, along with the three cases described above, form a triangle in the heart of Western Europe. Additional wild bird deaths in the Czech Republc are under investigation.
The multi-focal appearance of H5N1 in western Europe in June is consistent with the widespread outbreaks in western Europe in February, 2006. In both time periods, wild bird migration was minimal, and the vast majority of cases were in non-migratory birds. These data support an endemic condition, which is sporadically detected by a surveillance program in need of a significant upgrade.
Poor surveillance was clear when all countries in western Europe failed to detect H5N1 migration into the region in the fall of 2005. H5N1 was reported in the Volga Delta, the Danube Delta, and western Turkey in 2005. It was also present in the Nile Delta in December, 2005, but was not reported until the fall of 2006 because low levels blunted initial sequencing attempts. Moreover, the sequence in the healthy teal in Egypt matched sequences subsequently found in Austria, further supporting an earlier introduction into western Europe.
In addition to failing to detect H5N1 in the fall of 2005, detection of H5N1 between June of 2006 and June of 2007 has been minimal. Although it is not clear why H5N1 is now being detected, the continued presence of H5N1 in the region is clear.
Sequence data on the new isolates will be useful.
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