Submitted to: Book Chapter
Publication Type: Book / Chapter
Publication Acceptance Date: July 24, 2007
Publication Date: March 1, 2008
Citation: Swayne, D.E., Pantin Jackwood, M.J. 2008. Pathobiology of avian influenza virus infections in birds and mammals. In: Swayne, D.E., editor. Avian Influenza. Ames, Iowa: Blackwell Publishing. p. 87-122. Technical Abstract: A variety of AI viruses have caused infections in birds and mammals resulting in varying clinical and pathobiological features depending on multiple factors, including host species and virus strain. LPAI virus typically produced clinical signs and lesions in the respiratory and intestinal tracts of domestic poultry. By contrast, HPAI viruses typically produce a similar severe, systemic disease with high mortality in chickens and other gallinaceous birds. However, these same HPAI viruses usually produce no infections or limited infection with no clinical signs or only mild disease in domestic ducks and wild birds. Over the past decade, the emergent H5N1 HPAI viruses have shifted to increased virulence for chickens as evident by shorter MDT and a greater propensity for massive disseminated replication in vascular endothelial cells. These viruses have changed from producing inconsistent respiratory infections in ducks to some strains being highly lethal in ducks with virus found in multiple visceral organs and brain. The most recent Asian H5N1 HPAI viruses have also infected some wild birds producing systemic infections and death. Across all bird species the ability to produce severe disease and death is associated with high virus replication titers in the host, especially in specific tissues such as brain and heart. The AI viruses on occasion have caused infection in a number of mammalian species, including humans, domestic cats, dogs, and large felids. Experimental infection with AI viruses has produced pathological changes which varied depending on the animal species and the virus strain.