Title: Current status and future needs in diagnostics and vaccines for high pathogenicity avian influenza Authors
Submitted to: Developments in Biologicals
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 1, 2012
Publication Date: January 13, 2013
Citation: Swayne, D.E., Spackman, E. 2013. Current status and future needs in diagnostics and vaccines for high pathogenicity avian influenza. Developments in Biologicals. 135:79-94. Interpretive Summary: Highly pathogenic avian influenza (HPAI) has caused 31 deadly outbreaks in poultry over past 50 years, with culling of infected poultry being the most widely used control method. However, vaccine has been used as a control measure in a limited number of outbreaks, mostly in developing/transition countries with over 113 billion doses being used. H5N1 HPAI has occurred in countries that vaccinate poultry because of vaccine failures, but more commonly these problems have resulted from the inability to catch and inject all the poultry in the country. China and other developing/transition countries will drive innovation and implementation of new vaccines. Rapid molecular test has shorten time to find HPAI, and accelerated eradication efforts.
Technical Abstract: Since 1959, 31 epizootics of high pathogenicity avian influenza (HPAI) have occurred in birds. Rapid detection and accurate identification of HPAI has been critical to controlling such epizootics in poultry. Specific paradigms for the detection and diagnosis of avian influenza virus (AIV) in poultry vary somewhat among different countries and industry compartments depending on specific needs and resources. Importantly, since HPAI and low pathogenicity (LP) AI of the H5 and H7 subtypes are reportable to World Organization for Animal Health (OIE), diagnostic procedures are implemented for regulatory purposes and are harmonized to some degree. Most current tests are adequate and have been in use for some time, therefore they have been well validated and presently there is no reported new technology that will completely replace the current tests. However, some modifications, updates or additional tests could be beneficial. The element of AIV diagnostics that is most in need of improvement is in determining the hemagglutinin and neuraminidase subtype specificity of antibody to AIV. Most HPAI epizootics have been eradicated using traditional stamping-out programs, but beginning in 1995, five epizootics have added vaccination as an additional, interim control tool. From 2002-2010, >113 billion doses of AI vaccine have been used in poultry; 95.5% as oil-emulsified, inactivated whole AIV vaccines and 4.5% as live vectored vaccines. The majority of vaccine has been used in the four H5N1 HPAI enzootic countries (China [91%], Egypt [4.7%], Indonesia [2.3%], and Vietnam [1.4%]) where vaccination programs are directed to all poultry. The 10 other countries/regions have used less than 1% of the vaccine, administered in a focused, risk-based approach. Some vaccine “failures” have resulted from antigenic drift of field viruses away from the vaccine viruses, but most have resulted from failures in the vaccination process; i.e. failure to adequately administer the vaccine to at risk poultry resulting in lack of population immunity. China, as the major AIV vaccine user, will drive innovation and commercialization of new vaccine technologies, but because of the low-cost to manufacture the current high quality inactivated whole AIV vaccines, such vaccines will continue to dominate the market for the next 10 years.