Viral pneumonia pathophysiology

Editor-In-Chief: C. Michael Gibson, M.S., M.D. [1]

• Viruses must invade cells in order to reproduce.
• Typically, a virus will reach the lungs by traveling in droplets through the mouth and nose with inhalation.
• There, the virus invades the cells lining the airways and the alveoli.
• This invasion often leads to cell death either by directly killing the virus or by self-destruction through apoptosis.
• Further damage to the lungs occurs when the immune system responds to the infection. White blood cells, in particular lymphocytes, are responsible for activating a variety of chemicals (cytokines) which cause leaking of fluid into the alveoli.
• The combination of cellular destruction and fluid-filled alveoli interrupts the transportation of oxygen into the bloodstream.
• In addition to the effects on the lungs, many viruses affect other organs and can lead to illness affecting many different bodily functions.
• Viruses also make the body more susceptible to bacterial infection; for this reason, bacterial pneumonia often complicates viral CAP.

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