Bronchiectasis
Causes

In some cases of bronchiectasis there is no obvious cause. However, there are a number of known causes of bronchiectasis:

• acid from the stomach that is regurgitated and inhaled can damage the bronchial tubes,
• inhaling poisonous gases may damage the tubes,
• a foreign body for example, a peanut can damage the bronchial tubes. If the item is removed quickly, any damage (including bronchiectasis) can usually be avoided,
• some genetic conditions for example cystic fibrosis, where the mucus in the bronchial tubes is too thick, and primary ciliary dyskinesia, where the cilia lining the bronchial tubes do not work properly,
• an allergy to fungus spores which can inflame the bronchial tubes,
• a defect of the immune system for example a deficiency of immunoglobulins (which protect against infection), and 
• a severe respiratory infection (for example pneumonia, whooping cough or measles), especially in childhood, can damage the airways and lead to bronchiectasis in early adulthood.