Author
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Swayne, David |
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Submitted to: Poultry Science
Publication Type: Abstract Only Publication Acceptance Date: 3/5/2004 Publication Date: 6/1/2004 Citation: Swayne, D.E. 2004. Avian Influenza, Vaccines and Control. Poultry Science 83(Suppl 1) p79, 2004. Interpretive Summary: Technical Abstract: Avian influenza (AI) is a viral disease of birds caused by type A orthomyxoviruses. Avian influenza viruses are further classified into 15 different hemagglutinin (H1-15) and 9 different neuraminidase (N1-9) subtypes. Biologically, AI viruses can be of low (LP) or high pathogenicity (HP) for chickens and related poultry species. Dealing with AI has focused on one of three goals: prevention, management (control) or eradication. In most developed countries, LPAI and HPAI are not common in commercial poultry and thus prevention is the primary goal. However, if AI occurs, eradication is the overall goal with epizootics of HPAI being eradicated through a strategy that includes enhanced biosecurity, surveillance or diagnostics to identify infected farms, quarantine of infected premises, depopulation and disposal of infected poultry, and cleaning and disinfection of infected premises. Vaccines have been used to manage economic losses from LPAI or, in some instances, have been used as a tool in LPAI or HPAI eradication strategies. AI vaccines can prevent clinical signs and death in poultry, increase resistance of birds to infection, and decrease the amount of virus shed in the environment. However, vaccines alone will not eradicate AI. High pathogenicity AI impacts international trade as does some forms of LPAI. Experimental studies in chickens have shown that LPAI viruses cause respiratory and gastrointestinal infections without infecting the meat. By contrast, HPAI viruses produce infection of respiratory and gastrointestinal tracts, produce a viremia and virus is present in the meat and internal contents of eggs during the acute stages of the infection. Additional experimental studies have demonstrated that pasteurization of liquid egg products using USDA guidelines will inactivate HPAI virus that have been artificially added to levels in excess of those reported in eggs laid by HPAI virus-infected hens. Although, no virus has been demonstrated in internal contents of eggs laid by LPAI virus infected hens, pasteurization has been shown to inactivate LPAI virus artificially added to egg products. |
