Swine influenza classification

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

Swine influenza may be classified according to the genera of the infective agent into either influenza A (common) or influenza C (rare). Influenza B has not been associated with development of swine influenza.

Swine influenza may be classified according to the genera of the infective agent into either influenza A (common) or influenza C (rare). Influenza B has not been associated with development of swine influenza.

• Influenza A subtypes include the following:

• H1N1
• H1N2
• H2N3
• H3N1
• H3N2

A new strain of H1N1, A/Veracruz/2009, emerged in 2009 and was responsible for the 2009 swine influenza outbreak in humans.

• Influenza C has been described in a few case reports in the USA and Japan.
• Influenza C is not thought to be genetically diverse, and accordingly it has not been associated with outbreaks among humans.