Most avian influenza (AI) viruses are low pathogenic, meaning they cause only mild clinical signs in a few birds. The current outbreak of HPAI H5N1 is the largest and most severe AI outbreak in poultry on record. Many countries in the Far East, Africa, and Europe have been affected at the same time. Unprecedented numbers of domestic poultry have been lost due to the disease or culling of infected flocks. Please visit the extension website for a list of major outbreaks in poultry.
Despite dramatic control measures, including mass culling, quarantine of farms, and (in some countries) vaccination of poultry, the disease is considered endemic (established) in many countries. The disease has also infected more than 400 humans in 15 countries since 2003, 60% of whom have died. Please visit the extension website for a list of confirmed human cases of avian influenza.