Diagnosing aspergillosis can be challenging. This is because aspergillosis is not one single disease, and because its symptoms often overlap with asthma, bronchiectasis, chronic obstructive pulmonary disease (COPD), bacterial infection and other lung conditions.
Doctors usually diagnose aspergillosis by combining several different types of information. These may include symptoms, scans, blood tests, sputum results and a person’s underlying lung or immune condition. One test alone is often not enough.
This page gives an overview of how aspergillosis is diagnosed and explains the main types of evidence doctors use.
Key Points
- Diagnosis usually depends on a combination of evidence rather than one single test.
- The tests used depend on the type of aspergillosis being considered.
- Some tests look for the fungus itself, while others look for the body’s immune response.
- Scans are often very important, especially in chronic lung disease.
- Diagnosis may take time because results need to be interpreted together.
Why Diagnosis Can Be Difficult
Aspergillosis can be difficult to diagnose for several reasons. Many symptoms are non-specific, including cough, fatigue, breathlessness and sputum production. Some people already have pre-existing lung disease, which can make it harder to know what is causing their symptoms.
In addition, different forms of aspergillosis need different types of evidence. For example, allergic conditions such as Allergic Bronchopulmonary Aspergillosis (ABPA) rely heavily on blood tests and clinical history, while chronic infections such as Chronic Pulmonary Aspergillosis (CPA) often depend strongly on CT findings and longer-term changes in the lungs.
The Main Streams of Evidence
Doctors often build the diagnosis from several streams of evidence:
- Symptoms and clinical history – what symptoms are present, how long they have been there, and whether there is asthma, bronchiectasis, previous tuberculosis, immune suppression or other risk factors
- Imaging – chest X-rays and especially CT scans can show cavities, nodules, mucus plugging, bronchiectasis or other patterns that support the diagnosis
- Blood tests – these may look for immune responses to Aspergillus, such as raised Immunoglobulin E (IgE), Aspergillus-specific antibodies, or markers of inflammation
- Sputum or airway samples – these may detect Aspergillus growing in the airways or identify fungal material using culture or molecular tests
- Underlying health factors – the state of the immune system and lungs often helps determine which type of aspergillosis is most likely
Symptoms and Medical History
The starting point is often the person’s symptoms and medical background. Doctors may ask about:
- persistent cough
- breathlessness
- wheezing
- fatigue
- weight loss
- coughing up mucus or blood
- history of asthma, bronchiectasis or previous lung infection
- medicines that weaken the immune system
These details help doctors decide which tests are most useful and which form of aspergillosis may be present.
Imaging: CT Scans and Chest X-rays
Imaging is often central to diagnosis, especially in chronic lung disease. CT scans can show much more detail than a standard chest X-ray.
Depending on the condition, imaging may show:
- mucus plugging in the airways
- bronchiectasis
- cavities in the lungs
- aspergillus nodules
- areas of inflammation or infection
These findings need to be interpreted alongside the rest of the clinical picture.
Blood Tests
Blood tests are often used to look for the body’s immune response to Aspergillus or for evidence that supports infection or allergy.
Tests may include:
- Total Immunoglobulin E (IgE) – often important in allergic disease
- Aspergillus-specific IgE – helps support allergic sensitisation
- Aspergillus Immunoglobulin G (IgG) – often useful in chronic infection
- Eosinophils – may be raised in allergic conditions
- Inflammatory markers – sometimes used as part of the wider assessment
Different blood tests matter more in different conditions. For example, allergic conditions rely more on Immunoglobulin E (IgE) and eosinophils, while chronic infection often relies more on Aspergillus Immunoglobulin G (IgG) and imaging.
Sputum and Airway Samples
Sputum can sometimes provide direct evidence of Aspergillus in the airways. Samples may be examined in different ways, including fungal culture and molecular tests.
However, interpretation can be difficult. Finding Aspergillus in sputum does not always prove that it is causing disease, because some people may breathe in spores or have the fungus present without it being the main cause of symptoms. This is why sputum results are interpreted alongside the rest of the evidence.
Tests for the Fungus vs Tests for the Immune Response
Some tests try to detect parts of the fungus itself. Others look at how the body is reacting to the fungus.
Tests looking for the fungus may include sputum culture, microscopy, molecular tests and some fungal biomarkers.
Tests looking at the immune response may include total Immunoglobulin E (IgE), Aspergillus-specific Immunoglobulin E (IgE), Aspergillus Immunoglobulin G (IgG), and eosinophil counts.
Both types of evidence matter, but the balance depends on whether the doctor is considering allergic disease, chronic infection or invasive infection.
Diagnosis in Different Types of Aspergillosis
Allergic disease
In conditions such as Allergic Bronchopulmonary Aspergillosis (ABPA) and Severe Asthma with Fungal Sensitisation (SAFS), diagnosis often depends on a combination of asthma or airway disease, blood test results and imaging.
Chronic infection
In conditions such as Chronic Pulmonary Aspergillosis (CPA), Aspergillus bronchitis and aspergillus nodules, diagnosis often depends on symptoms over time, imaging findings and supportive microbiology or antibody results.
Invasive infection
Invasive aspergillosis is usually considered in people who are very unwell or severely immunocompromised. In this setting, diagnosis may need to happen quickly using scans, laboratory tests and the overall clinical picture.
Why Diagnosis Sometimes Takes Time
Many people feel frustrated when diagnosis is not immediate. This is understandable. Aspergillosis often requires careful interpretation of several test results together, and doctors may need to monitor symptoms, repeat scans, or wait for laboratory results before reaching a firm conclusion.
In some cases, the diagnosis becomes clearer over time rather than at a single appointment.
Common Questions
Can one blood test diagnose aspergillosis?
Usually not. Blood tests are important, but they are normally interpreted together with symptoms, scans and other results.
Why do I need a CT scan?
CT scans can show details in the lungs that are not visible on a standard chest X-ray and are often very important in chronic aspergillus lung disease.
If Aspergillus is found in my sputum, does that prove I have disease?
Not always. It can be an important clue, but it needs to be interpreted in context.
Why do different doctors mention different tests?
Because the most useful tests vary depending on whether they are considering allergic disease, chronic infection or invasive infection.
Where to Go Next
- What is Aspergillosis?
- Which Type of Aspergillosis Do I Have?
- Symptoms of Aspergillus Disease
- Treatment and Management
- Search the Knowledge Hub
Last reviewed: March 2026