Avian Influenza — Worldwide/Unknown
Recent studies have shown that [highly pathogenic influenza virus] Asian H5N1 does not cause severe disease in all bird species and some may carry the virus asymptomatically and thus serve as reservoirs for the virus. Thus, the virus could then be carried to novel regions.
Movement of the virus by migratory birds is thought to have led to the novel emergence of H5N1 in Japan in spring of 2008. Also, there are _Anas_ species that use migratory routes between Asia and Alaska. The northern
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