The respiratory tract has a remarkable defense system to protect against the numerous potential hazards we breathe in each day, but sometimes bacteria, viruses, or other microorganisms overwhelm this defense system and cause a respiratory infection.

There are many different types of respiratory infections, the most common of which are acute bronchitis, influenza, and bacterial pneumonia.

The symptoms of a lung infection can overlap with those of a noninfectious lung disease, making diagnosis difficult. In fact, people with noninfectious lung diseases are at increased risk for respiratory infections, either from the lung disease itself or from its treatment (corticosteroids, for instance).

Conversely, a respiratory infection may cause both scarring of the lungs and a decline in lung function, setting the stage for future and recurrent episodes of lung infection.

Publication Review By: Peter B. Terry, M.D., M.A.

Published: 19 Sep 2011

Last Modified: 15 Dec 2014