Submitted to: Avian Influenza Symposium International Proceedings
Publication Type: Proceedings
Publication Acceptance Date: November 2, 2007
Publication Date: December 11, 2007
Citation: Swayne, D.E. 2007. The changing ecology, epidemiology and pathobiology of avian influenza [abstract]. In: Proceedings of the 2007 HPAI International Symposium, December 11-13, 2007, Anyang, South Korea. p. 6-17.
Twenty-five epizootics of high pathogenicity avian influenza (HPAI) have occurred in the world since 1959. The largest of these outbreaks has been the H5N1 HPAI which has caused problems in poultry and some wild birds in over 60 countries of Asia, Europe and Africa since beginning in 1996. The H5N1 HPAI viruses have also caused severe infections and death in a few humans, but such infections have been rarely caused by other HPAI viruses. Natural infections of wild birds with HPAI virus was first reported in common terns in South Africa during 1961, with the H5N3 subtype. With the H5N1 HPAI virus first reported in China during 1996, wild bird infections were not initially reported, but beginning in 2002, in Hong Kong, a variety of fatal infections in various wild and captive waterfowl and wading birds was reported. In early 2005, large die-offs of wild waterfowl were reported in Qinghai China, followed by wild bird mortality in Mongolia and Siberia. The outbreaks were also reported in poultry in Siberia and Kazakhstan. In winter 2006, mortality was identified in waterfowl in several European Union countries with minimal cases in poultry. The HPAI viruses cause severe systemic infection in multiple poultry species and the viruses can be present in multiple internal organs, meat, eggs and blood. The most recent viruses from Vietnam also cause high mortality in young domestic ducks. Various wild aquatic birds have been infected by H5N1 HPAI viruses and experimental studies have shown high susceptibility of swans, geese and some gull species.