Since 1997 a new and more deadly strain of highly pathogenic avian influenza virus (A/H5N1) has appeared in domestic poultry and humans, initially in southern China where the first human-to-human transmission took place.
Alates 1997. aastast on kodulinnud ja inimesed nakatunud uude ja senisest surmavamasse suure patogeensusega linnugripiviirusse (A/H5N1), mis avastati algselt Lõuna-Hiinas, kus viirus kandus esimest korda inimeselt inimesele.