禽流感
Avian influenza caused by infection with H5N1, a highly pathogenic avian influenza virus (HPAIV), has spread in poultry in more than 60 countries in Eurasia and Africa since 1996, when the first outbreak occurred at a goose farm in Guangdong province in China. H5N1 in wild birds have spread to Asia, Europe, and Africa, and it is possible for the H5N1 virus to be spread by migratory water birds to the west and south, as genetically closely related H5N1 viruses have been isolated in several countries since 2005.