Submitted to: Meeting Proceedings
Publication Type: Proceedings
Publication Acceptance Date: 3/1/2013
Publication Date: 6/17/2013
Citation: Swayne, D.E. 2013. Prevention and control of avian influenza in Asia. In: Proceedings of the Poultry Respiratory Diseases In Asia – Diagnosis And Control Workshop, Bangkok, Thailand, June 17-18,2013. CDROM.
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 62 countries during the past 15 years. For 2011-2012, 19 countries reported outbreaks of H5N1 in domestic poultry, wild birds or both. The majority of the outbreaks occurred in Indonesia, Egypt, Vietnam, and Bangladesh, in decreasing order. The majority of the cases were H5N1 HPAI but outbreaks of H5N2 occurred in Chinese Taipei (chickens) and South Africa (ostriches), and an outbreak of H7N3 HPAI in Mexico (egg-type chickens). 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 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. Fewer outbreaks of Low pathogenicity notifiable avian influenza (LPNAI) have been reported than HPAI and only six countries used vaccine in control programs which accounted for 8.1% of the total H5/H7 AI vaccine usage. Stamping-out without vaccination has been the preferred method for HPAI control and eradication used successfully in 27 HPAI epizootics.