What Causes Bronchiectasis?

An injury to the walls of your airways usually causes bronchiectasis. A lung infection may cause this injury. For example, severe pneumonia (nu-MO-ne-ah), whooping cough or measles (now uncommon due to vaccination), tuberculosis, or fungal infections can injure the airways and lead to bronchiectasis.

Often, people who have bronchiectasis have an underlying condition that damages their airways and increases their risk for lung infections. Examples of such conditions include:

• Cystic fibrosis. This disease leads to almost half of the cases of bronchiectasis in the United States.
• Immunodeficiency disorders, such as common variable immunodeficiency and, less often, HIV and AIDS.
• Allergic bronchopulmonary aspergillosis (AS-per-ji-LO-sis). This is an allergic reaction to a fungus called aspergillus. The reaction causes swelling in the airways.
• Disorders that affect cilia (SIL-e-ah) function, such as primary ciliary dyskinesia. Cilia are small, hair-like structures that line your airways. They normally clear mucus (a slimy substance) out of your airways.

Other conditions, such as a blockage in your airways, also can lead to bronchiectasis. A blockage may be due to a growth, a noncancerous tumor, or something inhaled, such as a piece of a toy or a peanut that you inhaled as a child.

Congenital bronchiectasis is the result of a problem with how the lungs form in a fetus. This condition usually affects infants and children.