Bronchiectasis is a progressive condition that gets worse over time in a pattern often referred to as a vicious circle.
Your lungs are continually exposed to germs so your body has a number of sophisticated defence mechanism that are designed to keep the lungs sterile (germ free). However, occasionally these defences can be breached.
Your immune system will attempt to stop the spread of any infection by sending infection-fighting white blood cells to the location of infection.
These cells release chemicals that can cause surrounding tissue to become inflamed.
In some cases, inflammation can destroy the elastic-like tissue and muscles that surround the bronchi, leading to the bronchi to becoming wider.
This abnormal bronchi then becomes filled with an excess amount of mucus which can trigger persistent coughing and make the lung more vulnerable to infection. This in turn can result in further inflammation, and further widening of the bronchi, leading to more mucus gathering and so it continues. However, the levels of damage to the lungs can differ widely from case to case.
In around half of all cases of bronchiectasis, no obvious cause can be found to explain what triggered the symptoms. Other triggers are described below.
Childhood infections
Around a third of cases of bronchiectasis currently found in adults are associated with a previous severe childhood lung infection, such as:
As there are now vaccinations available for these types of conditions, the rates of these types of infection-related bronchiectasis are expected to fall in the future.
Immunodeficiency
Around 1 in 12 cases of bronchiectasis are caused because a person has a weakened immune system – the body’s defence against infection – making their lungs more vulnerable to tissue damage. The medical term for having a weakened immune system is immunodeficiency.
Some people are born with an immunodeficiency due to problems with the genes that they inherit from their parents. It is also possible to acquire an immunodeficiency due to an infection such as HIV.
Allergic bronchopulmonary aspergillosis (ABPA)
Around 1 in 14 people develop bronchiectasis as a complication of an allergic condition known as allergic bronchopulmonary aspergillosis (ABPA).
People with ABPA have an allergy to a type of fungi known aspergillus, which is found in a wide range of different environments across the world.
If a person with ABPA breathes in fungal spores it can trigger an allergic reaction and persistent inflammation which in turn can progress to bronchiectasis.
Read more about allergic bronchopulmonary aspergillosis.
Aspiration
The medical term for accidentally swallowing the “wrong way” into your lungs rather than down into your stomach is aspiration, which is responsible for around 1 in 25 cases of bronchiectasis.
The lungs are very sensitive to the presence of foreign objects, such as small samples of food or even stomach acids, so this can trigger inflammation leading to bronchiectasis.
Young’s syndrome
Young’s syndrome is a rare disorder that accounts for around 1 in 33 cases of bronchiectasis and only affects males. The condition damages little tiny, hair-like structures that cover the airways in the lung known as cilia. The cilia are designed to protect the airways of the lungs, as well as helping move away any excess mucus.
Damage to the cilia can lead to the symptoms of bronchiectasis.
Young’s syndrome is thought to be caused by childhood exposure to mercury. As the regulations regarding the use of mercury are now much stricter than they were in the past it is expected that Young’s syndrome will become a much less common cause of bronchiectasis.
Cystic fibrosis
Cystic fibrosis is a relatively common genetic disorder where the lungs become clogged up with mucus. The mucus then provides an ideal environment for a bacterial infection to take place, leading to the symptoms of bronchiectasis.
It is estimated that cystic fibrosis is responsible for around 1 in 35 cases of bronchiectasis.
Rheumatoid arthritis
Rheumatoid arthritis is a common condition in which the immune system goes wrong and starts attacking healthy tissue, causing inflammation which in most cases is confined to the joints. However, in a small number of cases the inflammation can spread to the lungs, triggering the symptoms of bronchiectasis.
It is estimated that rheumatoid arthritis is responsible for around 1 in 35 cases of bronchiectasis.