Sources of Influenza A and Influenza B

Influenza A is the most common acute infectious disease worldwide, primarily caused by Influenza A virus, with three main subtypes: H1N1, H3N2, and Influenza B virus. The origin of the virus involves cross-species transmission from animals to humans, mainly from poultry to humans. This cross-species transmission may occur because poultry carry various influenza viruses that can mix and transmit to humans, and frequent human contact with poultry likely facilitates such transmission. Influenza B is caused by a newly emerged strain of Influenza B virus, which was first identified by scientists after 2009. Influenza B virus is globally widespread and more harmful than Influenza A virus, as well as more easily transmissible among humans. The origin of Influenza B also lies in cross-species transmission from animals to humans, primarily from pigs to humans. Research has found that influenza viruses in pigs may interact with those found in poultry, resulting in a new Influenza B virus that is more harmful than Influenza A.