CPA – Chronic Pulmonary Aspergillosis
CPA is a long term Aspergillus infection of the lung; Aspergillus fumigatus is almost always the species responsible. Sufferers of CPA have healthy immune systems which, under usual circumstances, would completely eradicate an infection. Consequently the fungus cannot rapidly invade the patient, but manages to inhabit areas of the body where it can find a toehold.
Suitable areas of the body for infection are where the fungus has first managed to gain access; the airways or sinuses are common, as fungal spores travel well in air. Secondly, it needs to evade the immune system, so tends to inhabit cavities where there is less contact with the immune system – such as damaged lung tissue left behind by tuberculosis or a similar infection. The debris left behind by the original infection provides the ‘toehold’ that the fungus needs.
Once established, the fungus can grow slowly, limited by the tissue surrounding the cavity (where the patient’s immune system can still fight the infection). It can lie hidden for years giving few symptoms but, in some cases can start to erode the surrounding tissue – perhaps because of scarring caused by inflammation where the fungus touches the sides of the cavity. This is how a fungal ball, also called an aspergilloma, develops. Not all CPA patients develop an aspergilloma.
This is not immediately health-threatening, unless a major blood vessel is eroded and bleeding occurs. Occasionally heavy blood loss can occur; this is called haemoptysis and immediate hospital treatment is required.
NB: Chronic Pulmonary Aspergillosis (CPA) and Chronic Invasive Pulmonary Aspergillosis (CIPA) have both been used in the past and this caused confusion. CIPA is now officially no longer used to describe this illness. Invasive aspergillosis is a different illness.
Chronic Pulmonary Aspergillosis covers at least three subcategories of chronic infection:
- Chronic Cavitary Pulmonary Aspergillosis (CCPA) which is defined by one or more cavities, with or without a fungal ball present.
- Aspergilloma is the term used for a fungal ball growing in a cavity. A CPA patient with an aspergilloma may see an improvement or little change over a few years. There may be few symptoms or just a cough.
- Chronic Fibrosing Pulmonary Aspergillosis (CFPA) is essentially CCPA that has got to a late stage in its development and the lung is heavily scarred.
Patients with aspergillomas have few specific symptoms, but 50-90% experience some coughing up of blood.
For other CPA sufferers, symptoms may include weight loss, fatigue, cough, haemoptysis (bleeding in the lungs) and breathlessness, usually for a period longer than 3 months.
Most patients with CPA have an underlying lung disease. These include TB, previous treatment for lung cancer, sarcoidosis, emphysema and COPD. Chest X-rays or CT scans may show one or more lung cavity, and blood tests may be positive for Aspergillus antibodies. A galactomannan assay is a more reliable test for Aspergillus exposure. A sample of sputum may be cultured in an attempt to see if Aspergillus grows. Occasionally a biopsy is taken & tested.
Diagnosis is difficult and often requires a specialist. This is one of the main services offered by the National Aspergillosis Centre in Manchester, UK, where advice can be sought.
Patients with single aspergillomas generally do well with surgery and are best given pre- and post-operative antifungals to prevent other complications. For more complex cases (CCPA), lifelong use of antifungals is normal, along with regular X-rays to observe progress. It is important to monitor the blood levels of antifungals to ensure optimal dosing, as individuals vary in how their bodies process these drugs.
If bleeding is occurring and surgery is not possible then other treatments can be used to limit blood loss. For example, tranexemic acid can be given to encourage clotting. If that fails, and bleeding becomes excessive, embolisation is carried out via a catheter (see talk about limiting blood loss by Consultant Radiologist at National Aspergillosis Centre Ray Ashleigh).
For most patients CPA will be a lifelong illness. 84% of patients do well post-surgery, if it is an option. In less than 10% of cases the disease spontaneously disappears. The vast majority of patients with CPA require chronic disease management. In most, the key aims of therapy are to reduce symptoms and prevent progression of the disease. Occasionally patients are both asymptomatic and do not progress even without therapy. At the other end of the spectrum are highly symptomatic patients, whose disease appears to progress despite high intensity antifungal therapy, sometimes with combined immunotherapy. Arresting progression, and in particular minimising loss of lung function, is a key goal of therapy, unfortunately not always achieved; likewise weight gain, reduction in fatigability, reduced cough, sputum production, haemoptysis and breathlessness are all valuable benefits of long-term antifungal therapy, also not always achieved.
There is a paper describing all aspects of CPA on the Aspergillus Website. Written by Professor David Denning (Director of the National Aspergillosis Centre) and colleagues, it is intended for people with medical training.