"A strain of highly pathogenic avian influenza (H5N1) has spread throughout Asia since 2003, infecting mostly poultry but also a limited number of humans. The virus reached Europe in 2005, and the Middle East and Africa in 2006. Officials believe this strain may enter North America later in 2006 through migratory flyways. Avian flu is highly contagious in domestic poultry, prompting strict biosecurity measures. International trade restrictions can cause significant economic effects. A different strain of H5N1 was found in wild swans in Michigan in August 2006. This low pathogenicity strain does not pose the same threat as highly pathogenic H5N1. Controlling avian flu in poultry is seen as the best way to prevent a human pandemic from developing, by reducing the number of animal hosts in which the virus may evolve. This report mainly covers avian flu in poultry, and will be updated."
CRS Report for Congress, RS21747
National Agricultural Law Center http://www.nationalaglawcenter.org/crs/