1、1 Pathogenicity is determined by genetic sequencing, and by inoculating healthy chicks andmonitoring them. HPAI mortality ranges from 30-100%; LPAI mortality is usually less than 20%.2 Surface proteins, called hemagglutinin and neuraminidase, are abbreviated H and N. SixteenH subtypes and nine N sub
2、types have been identified. They can occur in any combination.Congressional Research Service The Library of CongressCRS Report for CongressReceived through the CRS WebOrder Code RS21747Updated August 29, 2006Avian Influenza: Agricultural IssuesJim MonkeAnalyst in Agricultural PolicyResources, Scienc
3、e, and Industry DivisionSummaryA strain of highly pathogenic avian influenza (H5N1) has spread throughout Asiasince 2003, infecting mostly poultry but also a limited number of humans. The virusreached Europe in 2005, and the Middle East and Africa in 2006. Officials believe thisstrain may enter Nort
4、h America later in 2006 through migratory flyways. Avian flu ishighly 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 p
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