The Epidemiology of Swine Influenza Virus in the World and Its Public Health Implication

Abstract:

Swine influenza virus (SIV) is one of the major pathogens associated with swine respiratory disease. The co-infection between SIV and other pathogens make the epidemic situation even more complex, so far the SIV have spread throughout the world. Pigs play an important role in the evolution and ecology of influenza A virus. Due to their susceptibility to both avian and human influenza viruses, pigs have been postulated to serve as an intermediate host for the interspecies transmission of avian influenza viruses to humans or as a “mixing vessel” for the generation of human, avian, and/or swine reassortant viruses. Currently, three predominant subtypes of influenza virus are prevalent in pig populations worldwide: H1N1, H3N2, and H1N2, and these include classical swine H1N1, avian-like H1N1, human-like H3N2, reassortant H3N2 and various genotype H1N2 viruses. There is evidence suggesting that avian influenza viruses had been transmitted to pigs in China. Introduction of avian viruses into pigs co-infected with human H3N2 or swine H1N1 viruses provide a favorable opportunity for the generation of reassortants containing avian genes and would thereby pose a significant pandemic threat to pigs farming and human health.