**7. One health perspective**

The first influenza A virus pandemic in humans was recorded almost a century ago, in 1918, which resulted in the death of around 20–50 million humans worldwide [20, 21]. So far, three other pandemics of influenza A virus in humans that have caused considerable loss include the 1957 H2N2 pandemic, the 1968 H3N2 pandemic, and the 2009 H1N1 pandemic [22]. From East Asia to Southeast Asia, sporadic human infection of H5N1 viruses was reported in 2003–2004 along with outbreaks in the poultry [21].

H5N1 viruses have been reported from domesticated poultry and wild birds in Asia, North Africa, Central Africa, and Europe [23]. The transmission of HPAI H5N1 viruses from poultry to humans was first documented in 1997 in Hong Kong. Some subtypes of avian influenza virus such as H5, H7, H9, and H10 have the capability of interspecies transmission [18]. According to the World Health Organization, the total confirmed human cases of H5N1 infection to date are 860 with 454 fatal cases [24]. In 2013, a LPAI H7N9 virus caused an outbreak in China with a 36% case fatality [25]. Influenza viruses are a permanent threat for humans as well as birds.
