Epidemiology of avian influenza

While in the past decade the epidemiology of both low and highly pathogenic avian influenza (LPAI/HPAI) has changed considerably, much was learned from newly established global surveillance systems to monitor LPAI and HPAI viruses in migratory birds. LPAI H9N2 viruses that cause health problems in poultry in Eurasia and Africa could not be brought under control. Several major outbreaks of HPAI occurred in Europe and Canada, with serious implications for animal and often human health. The unprecedented spread of the HPAI H5N1 viruses throughout Eurasia and Africa became a major public health threat, as hundreds of people were hospitalised and more than 210 died. The risk that the current HPAI H5N1 or another emerging avian influenza virus may soon create the first influenza pandemic of the 21st century is widely appreciated. The current spread of H5N1 viruses also has major implications for animal health, animal welfare, food supplies, economies and biodiversity. Intervention strategies should focus foremost on the surveillance of LPAI and HPAI viruses in animals and humans, to provide early warning systems and virus repositories that will allow the timely establishment of seed viruses for candidate animal and human vaccines.