Orthomyxovirus of type A; is the most common pathogen of influenza epidemics.
Influenza A viruses damage the mucous membrane, thus facilitating bacteria to enter the body. The have a spike-like surface structure formed by the glycoproteins hemagglutinin (HA) and neuraminidase (NA). So far, there have been 16 hemagglutinin and 9 neuraminidase subtypes identified, which may occur in any combination. Influenza A viruses are able to remain infectious on inanimate surfaces for 24 hours. From there, they may be transferred and spread via the hands.