[Pneumonia and acute respiratory distress syndrome due to pandemic influenza H1N1 2009]

Abstract

Pandemic influenza H1N1 2009 caused more severe diseases in children and young adults than seasonal influenza. The typical manifestation of severe diseases was diffuse viral pneumonia complicated with acute respiratory distress syndrome. Over half of the severe cases had underlying conditions, in which pregnancy and morbid obesity were regarded as major risk factors. Pathological findings revealed that the virus efficiently replicated in alveolar cells and caused diffuse alveolar damage as well as bronchiolitis. The level of plasma cytokines was also elevated in the severe cases. Antiviral use was generally recommended for the severe cases and might improve the outcomes. Further studies are needed for better clinical management of the severe cases of the latest pandemic influenza.