Author
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Swayne, David |
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Submitted to: Annual Asian Pacific Poultry Conference
Publication Type: Proceedings Publication Acceptance Date: 9/1/2014 Publication Date: 10/19/2014 Citation: Swayne, D.E. 2014. Global expansion of high pathogenicity avian influenza: implications on prevention and control programs. In: Proceedings of 10th Asia Pacific Poultry Conference, October 19-23, 2014, Jeju Island, South Korea. p. 40-43. Interpretive Summary: Technical Abstract: The H5N1 high pathogenicity avian influenza (HPAI) virus emerged in China during 1996 and has spread to infect poultry and/or wild birds in 63 countries during the past 18 years. The majority of the recent outbreaks of H5N1 HPAI have occurred in Indonesia, Egypt, Vietnam, and Bangladesh, in decreasing order. The majority of the HPAI cases were H5N1 HPAI but outbreaks of H5N2 occurred in Chinese Taipei (chickens) and South Africa (ostriches), an outbreak of H7N3 HPAI in Mexico (egg-type chickens), an outbreak of H7N7 HPAI in Australia (free range layers), an outbreak of H7N2 HPAI in Australia (free range chickens and layers), and an outbreak of H5N8 HPAI in South Korea and Japan (breeder and meat ducks). Field outbreaks of H5N1 HPAI have occurred in vaccinated flocks from both failure of the vaccines (i.e., vaccine efficacy) and failure in administration or immune response of the target species (i.e., vaccination effectiveness). Antigenic drift in field viruses has resulted in failure of protection by classic H5 vaccines strains in Mexico, China, Egypt, Indonesia, Hong Kong, and Vietnam. This challenge has been met by developing new vaccine strains that provide protection against ever changing HPAI viruses. A comprehensive review of AI control methods by World Organization for Animal Health has been completed. From 2002-2010, >113 billion doses of AI vaccine were used in poultry in 15 countries. The majority of vaccine (>91%) was used in China while significant amounts were used in Egypt, Indonesia, and Vietnam. Implementation of vaccination in these four countries occurred after H5N1 HPAI became endemic in domestic poultry and vaccination did not result in the endemic infections. The other 11 countries used less than 1% of the vaccine. Inactivated AI vaccines accounted for 95.5% and live recombinant virus vaccines for 4.5% of vaccine used. Clinical disease and mortality were prevented in chickens, and rural livelihoods and food security were maintained by using vaccines during HPAI outbreaks. Better surveillance is needed in vaccinated flocks and regions to identify foci of infection for eradication. |
