bird flu virus infections in humans, facts about avian influenza in humans

aiv avian bird birds concept conceptual confirmations diseases doctor facts fao flu genes genetics global h1n1 h5n1 h5n8 h7n7 h7n9 h9n2 health highly hospital hpai human humans illness illustrations infections influenza low lpai mortality mutation mutations oie outbreak outbreaks pandemic patient people person potential poultry rate reassortment reports sick situation strains symptoms threat treatment update vaccination vaccines virus viruses weekly wild zoonotic