Aim. To analyze clinical and morphological features of lethal outcomes in influenza A (H1N1) pdm09.

Methods. The article provides an analysis of 21 cases of death from severe complicated influenza A (H1N1) pdm09. A clinical example is presented. The diagnosis of influenza A (H1N1) pdm09 was laboratory-confirmed by polymerase chain reaction in vivo in nasopharyngeal swab samples. The diagnosis of influenza A (H1N1) pdm09 was also confirmed posthumously by polymerase chain reaction with detection of influenza virus antigens in autopsy materials.

Results. The deceased were 25 to 63 years old, were admitted on day 5 to 8 from the beginning of the disease (in average, 6.4±0.6 days), among them 12 (57%) females and 9 (43%) males. The risk factors were overweight and obesity in 18 (85.7%) patients. Lethal outcome occurred as a result of acute respiratory failure and acute respiratory distress syndrome. Morphologically severe total involvement of trachea, lungs and bronchi with congestion of internal organs was detected. Clinical manifestations of acute respiratory failure and acute respiratory distress syndrome were morphologically associated with alveolar damage. In all cases of death diffuse alveolar damage and multiple organ changes were diagnosed.

Conclusion. Severe course of influenza A (H1N1) pdm09, complicated with community-acquired viral and bacterial pneumonia, was associated with the development of infectious-toxic shock; lethal outcome occured as a result of ARF acute respiratory failure and acute respiratory distress syndrome; severe total involvement of trachea, lungs and bronchi with congestion of internal organs was confirmed morphologically.