Influenza and avian viruses: the latent threat of a new pandemic virus

The disease caused by avian influenza is a zoonosis. Migratory birds usually carry viruses in the respiratory or intestinal tract, they do not contract the infection, but are reservoirs of the virus. Avian viruses are usually specific to certain species, but on several occasions, they can infect man. Transmission to humans has occurred in close contact with infected non-migratory (poultry or poultry markets) birds or highly contaminated environments. Apparently, there is evidence of avian viruses that have infected the human since the 90's being the first to identify the AH5N1 in 1997 and then in 1999 the AH9N2, which is considered the highest potential pandemic alert. While it is true that the majority of infection and disease in humans have been secondary to the AH5 virus, there are different types of avian influenza that have caused mortality in humans, including among them the H5 viruses and their different subtypes, and others such as: AH7N7, AH7N9, H10N8 and the AH9N2. Avian flu disease should not be confused with seasonal human flu, which is a common human disease (usually caused by the H1 and H3 viruses). Given the pandemic potential of avian viruses, the objective of this review is to know their risk factors, transmissibility and epidemiology before the imminence of a new pandemic. So we must insist on constant vigilance in both animal and human populations, thoroughly investigating the risks of infection for timely planning in the event of a pandemic as the World Health Organization has been doing.