With estimated prevalence of 3–4 cases per 100,000 population, and far higher rates in high-risk groups.

Chronic Pulmonary Aspergillosis (CPA) is a slowly progressive fungal lung disease affecting an estimated 3–4 per 100,000 people in the UK, with higher estimates in global settings with greater TB prevalence. Despite this, many clinicians will go through entire careers without confidently recognising it — not because it is extremely rare, but because it almost always hides inside other long-term lung diseases.

The UK is unusual in having a nationally commissioned specialist service — the National Aspergillosis Centre (NAC), based at Wythenshawe Hospital, Manchester — offering funded diagnostics, multidisciplinary review, and long-term antifungal management. But only a fraction of expected CPA cases are ever referred. Most are simply never diagnosed.

This article explains why diagnoses are missed, who is at highest risk, which specialities need to be more alert, and the red flags that should trigger testing or referral.

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⭐ How Common Is CPA? The Numbers Behind the Problem

The UK prevalence is estimated at 3–4 per 100,000 people — approximately 2,000–2,500 people with CPA at any given time.

But the risk is far higher in specific groups:

Using these figures, the true UK caseload could exceed 4,000–6,000 individuals, yet NAC receives ~500–1,000 referrals, highlighting a large diagnostic gap.

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⭐ Why CPA Is So Often Missed

1. Symptoms mimic common chronic lung diseases

CPA presents with:

• Persistent cough

• Breathlessness

• Fatigue

• Weight loss

• Recurrent “chest infections”

• Haemoptysis

These overlap almost perfectly with:

• COPD

• bronchiectasis

• post-TB changes

• long COVID

• NTM infection

• repeatedly “slow to clear” pneumonia

Because symptoms are non-specific, clinicians rarely think fungal.

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2. Interpretation of imaging is inconsistent

CPA shows:

• one or more cavities

• pleural thickening

• nodules

• progressive changes over months

• fungal balls

Common reporting pitfalls:

• labelled “post-infective scarring”

• misinterpreted as malignancy

• seen but not compared longitudinally

• incidental CT findings not acted upon

Radiology is one of the biggest missed opportunities for early detection.

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3. IgG testing is not routinely requested

Aspergillus IgG is the key diagnostic biomarker — but it is:

• often confused with IgE

• not available in some hospitals

• omitted from workups for recurrent infection

• unfamiliar to non-respiratory clinicians

Without IgG, CPA is rarely diagnosed.

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4. Short-term improvement with antibiotics is misleading

Patients with CPA may temporarily feel better after:

• broad-spectrum antibiotics

• steroids

• physiotherapy

This transient improvement creates false reassurance.

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5. CPA spans multiple specialisms — and no one owns it

Diagnosis requires combined expertise across:

• respiratory medicine

• infectious diseases

• radiology

• microbiology

• immunology

When no one speciality takes responsibility, patients get lost.

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⭐ Which Patients Are at High Risk?

CPA almost always develops on a background of existing lung damage.

1. Post-TB lung disease (PTLD)

Globally the largest CPA population.
Residual cavities are the strongest predictor.

Specialities needing awareness:

• TB teams

• ID physicians

• Radiologists

• Community TB nurses

• Public health TB programmes

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2. COPD (especially severe / emphysema)

Millions of people are potentially at risk.
Recurrent infections + bullae/cavities = fertile ground for CPA.

Specialities:

• COPD clinics

• Pulmonary rehab

• Acute medicine (frequent admissions)

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3. Bronchiectasis

Damaged airways enable persistent Aspergillus colonisation and inflammation.

Specialities:

• Bronchiectasis MDTs

• Severe asthma & NTM clinics

• Respiratory physiotherapy

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4. Sarcoidosis and ILD

Fibrosis and traction bronchiectasis develop cavities over time.

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5. Post-COVID or post-influenza structural disease

Emerging risk group, especially in patients with:

• ventilatory lung injury

• persistent CT abnormalities

• chronic steroid exposure

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6. Chronic steroid or immunomodulator use

While invasive aspergillosis is linked to profound immunosuppression, CPA often affects those with milder, chronic immune dysfunction:

• systemic steroids

• high-dose inhaled steroids

• biologics affecting eosinophils

• poorly controlled diabetes

• chronic kidney disease

• malnutrition

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⭐ Which Specialities Need to Be More Alert?

• Respiratory Medicine – primary detection, but awareness varies greatly

• Infectious Diseases – especially post-TB and persistent infection clinics

• Radiology – key to spotting early changes

• Primary Care – sees patients repeatedly with “ongoing chest infections”

• Emergency & acute medicine – haemoptysis presentations

• Bronchiectasis and NTM services – strong overlap

• Severe asthma and biologics teams – ABPA → CPA evolution

• TB clinics – highest prevalence globally, often least recognised

The National Aspergillosis Centre should be the referral point for any complex or uncertain case.

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⭐ Red Flags: When to Suspect CPA

1. Cavities on CT (thin-, thick-walled, evolving, or multiple)

Especially with pleural thickening.

2. Haemoptysis

CPA is one of the most common causes of haemoptysis in people with cavities.

3. Symptoms lasting >3 months

Chronic cough, fatigue, weight loss, breathlessness.

4. “Recurrent infections” that never fully resolve

5. Post-TB patient with any new or worsening symptoms

6. Bronchiectasis patient with new cavity or Aspergillus culture

7. High or rising Aspergillus IgG

8. ABPA patient who deteriorates off antifungals

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⭐ The Cost of Missed Diagnoses

When CPA is not recognised early, the consequences are severe:

• irreversible lung damage

• repeated hospitalisations

• emergency haemoptysis events

• prolonged antifungal therapy with more toxicity

• reduced quality of life

• avoidable deaths

For systems like the NHS, late diagnosis increases costs:

• unplanned admissions

• repeated CT imaging

• prolonged antibiotics

• intensive care during haemoptysis

• complex surgery (lobectomy/pneumonectomy)

Early referral to specialist centres like the National Aspergillosis Centre prevents many of these harms.

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⭐ Conclusion

CPA is not rare within the populations most likely to develop it.
Missed diagnoses are common, predictable, and preventable.

By increasing awareness across Respiratory, Infectious Diseases, Radiology, Primary Care, TB services, and severe asthma pathways — and by using simple tools such as Aspergillus IgG and careful CT interpretation — clinicians can dramatically reduce the diagnostic delay that damages lungs, quality of life, and survival.

The UK is fortunate to have the National Aspergillosis Centre as a nationally commissioned referral service. Recognising CPA early and referring appropriately has the power to save lives, reduce system costs, and improve long-term outcomes.

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