historical_avian_influenza_outbreaks_bird_flu_spanish_flu_russian_flu_pandemics_h5n1_h1n1, 1997

pandemic history flu avian strain serotype 1878 1957 1967 vaccine outbreaks health poultry epidemiology h5n1 h1n1 h7n9 transmission epidemic zoonotic pathogen influenza immunization public spread mortality containment surveillance control prevention mutation biosecurity quarantine symptoms treatment virology immunity safety emergency medical 1918 historical disease 1997 china fowl