RESUMO
Influenza viruses cause annual epidemics that occur at different times in both the northern and southern hemisphere. In cases of seasonal influenza these are usually mild forms of the disease, which rarely lead to death of the patient. Vulnerable groups include the elderly, the young or those with comorbidities, where the virus affects tens of thousands of victims around the world. Occasionally, however, large epidemics appear caused by a dangerous variant of a new virus, which is usually characterized by high contagiousness and pathogenicity (virulence). Consequently, it is often accompanied by a complicated disease course and associated with high mortality. In 2009, a viral pandemic disease marked pH1N1 2009 Influenza A appeared. Even though the initial predictions were far worse, the course of influenza caused by this virus was often complicated by acute respiratory failure in the form of acute respiratory distress syndrome (ARDS). This formed part of the wider multiple organ failure syndrome (MODS). This type of virus often infects younger age groups and is more contagious compared to the seasonal flu. In order to illustrate the complicated forms of viral infections pH1N1 2009 Influenza A we present three case studies which demonstrate complicated pulmonary manifestation, which take the primary form of ARDS.