Health statistics are a very important element for analyzing health situation, the definition of policies and programs, decision making and evaluation of results. In particular, information on morbidity and mortality are directly reflected by the suffering of the population, indicating the necessary actions for prevention, treatment or rehabilitation.

   In late March 2009, an increase in severe acute respiratory infections (SARI) was observed in Mexico. In the week of 17-23 April, 854 probable cases of influenza with severe pneumonia were reported, with 59 deaths. The cases occurred in 19 of the country’s 32 states, with the greatest geographic concentration found in the Federal District, the State of Mexico, and the State of San Luís Potosí and, the greatest concentration in terms of age, in previously healthy young adults. During the initial stages of the outbreak, only a very few SARI patients were children under 3 or adults over 59. Analysis of 18 specimens obtained from patients and sent to the laboratory in Winnipeg, Canada, confirmed the influenza infection, with eight of them positive for the influenza A(H1N1) virus, genetically similar to the viruses isolated in the United States.