Many times I have said that migration of birds can and does account for significant spread of viruses all around the globe over vast distances.

This next article clearly demonstrates this fact with the detection of a rare form of avian influenza in Siberia, being found in a Teal duck from Australia.

This clearly demonstrates how our best efforts to contain an outbreak of H5N1 when it becomes H2H transmissible, will always be highly limited by these natural occurring annual migrations that will always tend to negate any attempts to hold this bug to any specific region, and regrettably these factors will in all probability significantly contribute to a pandemic result.

Influenza A (H15N4) Virus Isolation in Western Siberia, Russia
Mariya V. Sivaya,b, Tatiana Baranovichc, Vasiliy Y. Marchenkoa, Kirill A. Sharshova, Elena A. Govorkovac, Aleksander M. Shestopalova,b and Richard J. Webbyc,#
+ Author Affiliations

aState Research Center of Virology and Biotechnology “Vector”, Novosibirsk Region, Koltsovo, Russia
bNovosibirsk State University, Novosibirsk, Russia
cDepartment of Infectious Diseases, St. Jude Children's Research Hospital, Memphis, TN 38105-2794
ABSTRACT
The rarely identified influenza A viruses of H15 hemagglutinin subtype have been isolated exclusively in Australia. Here we report the isolation of an H15N4 influenza A virus (A/teal/Chany/7119/2008) in Western Siberia, Russia. Phylogenetic analysis demonstrated that the internal genes of the A/teal/Chany/7119/2008 belong to the Eurasian clade, and that the H15 and N4 genes were introduced into the gene pool of circulating endemic avian influenza viruses through reassortment events.

Link here...

[link to jvi.asm.org]