On the brink: H5N1 and the risk to human health

The avian influenza virus is a pathogen that has been well known to the scientific community ever since its first detection in 1996. Avian influenza is caused by a single-stranded RNA influenza A virus, and the current outbreak in North America is caused by the subtype H5N1, with waterfowl serving as its natural reservoir. Waterfowl are often migratory birds, resulting in the spread of H5N1 across the globe. The worldwide spread of the virus, along with its capacity to mutate led to diverse phylogenetic clades and subclades. H5N1 clade 2.3.4.4b was first detected in European and Asian wild populations in 2016, and then in Canada in 2021, with the characteristic of infecting not only birds but also marine and terrestrial mammals. For years, researchers have been monitoring cases of avian influenza across the world, and the high number of cases in both wild and domestic animals in the USA raises concerns about transmissibility to other mammalian species.