H5N1 (A/H5N1) is a subtype of the influenza A virus that can cause sickness in humans and many other animal species. It is the highly pathogenic causative agent of H5N1 flu, commonly known as avian influenza (“bird flu”). Even though there are other strains of bird flu, H5N1 was the first to infect people. Avian influenza, commonly known as bird flu, is a virus that can infect not just birds but also people and other animals. The most prevalent strain of avian flu is H5N1. It can easily infect people and other animals who come into contact with a carrier and is fatal to birds.
Infected birds spread the bird flu virus through their saliva, mucus, and excrement. Bird flu viruses may infect people by inhalation or touching something infected with the virus and then touching their eyes, noses, or mouths. Bird flu virus infections in humans have frequently been brought on by unprotected contact with infected birds or surfaces.
However, certain infections have been found in cases when there was no documented direct contact with diseased birds or their habitat. The avian flu virus spreads from one infected person to close contact very rarely and only to a small number of people, but these viruses have the potential to mutate and acquire the ability to easily travel between people.