In agreement with the World Organization of the Health (WHO), during the annual epidemics of influenza they become infected between 10-20 % of the total population, appearing from a feverish disease up to leading to the hospitalization and in some cases to the death. To unpredictable intervals and due to the nature of the virus, this one can acquire new genes of others virus of the influenza that they concern birds or porks, of it it turns out to be a new virus with a completely new subtype of IT (HE,SHE) HAS and NA, and if this one is transmitted efficiently of person-to-person can cause a pandemic.