Influenza and endemic viral pneumonia

Abstract

Viruses are a common and important cause of severe community-acquired pneumonia, and may lead to severe respiratory disease and admission to the intensive care unit. Influenza is the most common virus associated with severe viral pneumonia, although other important causes include respiratory syncytial virus, adenovirus, metapneumonia virus, and coronaviruses. Viral pneumonias tend to have a seasonal predilection and are often preceded by a typical viral prodrome. This article focuses on severe influenza pneumonia, including the 2009 H1N1 pandemic, and briefly discusses other causes of severe respiratory disease of viral etiology.

Keywords: 2009 H1N1; Acute lung injury; Acute respiratory distress syndrome; Influenza; Viral pneumonia; Viral pneumonitis.

Fig. 1

Portable chest radiograph from a patient with H1N1 2009 viral pneumonitis and acute respiratory distress syndrome, showing diffuse bilateral airspace opacities.

Fig. 2

Biopsy from a patient approximately 1 week into H1N1 2009 viral infection. This specimen demonstrates diffuse alveolar damage with hyaline membrane formation (hematoxylin-eosin, original magnification ×100).

Fig. 3

Biopsy from patient with H1N1 2009 viral pneumonitis, demonstrating acute lung injury in the organizing phase. Type 2 pneumocyte hyperplasia and alveolar macrophages are prominent (hematoxylin-eosin, original magnification ×40).