Avian influenza: past, present and future.

Avian influenza is not a new disease, but the emergence of high pathogenicity avian influenza (HPAI) viruses of the A/Goose/Guangdong/1/96 lineage (Gs/GD) has necessitated fundamental changes to prevention and control strategies for this disease. No longer just an avian disease, avian influenza is capable of causing severe disease in humans and is considered a potential human pandemic threat requiring One Health approaches. In addition, Gs/GD HPAI viruses have developed the capacity to be carried across and between continents by migratory birds. Given the persistence of the current A(H5N1) clade 2.3.4.4b viruses in wild birds, enhanced measures to prevent and control infection will be needed. In most countries, infection in poultry can be eliminated, although questions will remain about the sustainability of repeated stamping out. Systematic preventive vaccination should be seriously considered as a method for reducing the number of outbreaks. HPAI will not be eliminated from countries where Gs/GD viruses remain enzootic until major changes are made to the way that poultry are reared and sold, vaccination is improved and other factors that inhibit reporting and response are overcome. Currently, focus lies on Gs/GD HPAI, yet control of low pathogenicity avian influenza viruses also requires attention, including the development of vaccines that are appropriately matched to circulating strains of virus.