Aspergillosis is an infection caused by Aspergillus fumigatus fungi. These fungi (mold) are very common both indoors and outdoors, typically found in dead leaves, plant matter, soil, or compost. Most individuals are able to inhale the spores of the fungus on a daily basis without developing any symptoms. However, in some individuals, Aspergillus can lead to an allergic reaction, chronic lung disease, and an invasive disease that can spread to the brain, kidneys, or other organs. Types of aspergillosis include allergic bronchopulmonary aspergillosis (APPA), aspergilloma, chronic pulmonary aspergillosis, and invasive aspergillosis.
What is Allergic Bronchopulmonary Aspergillosis (ABPA)?
ABPA is a hypersensitivity or allergic reaction caused due to Aspergillus fungi. It is most common in people with asthma and cystic fibrosis. People with ABPA may also have other allergic conditions, including eczema, hay fever, hives, and sinusitis.
Individuals with asthma and cystic fibrosis tend to produce more mucus, and when they are exposed to Aspergillus mold it does not enter the lungs. Instead, Aspergillus colonizes the mucus present in the respiratory tract, which can result in recurrent inflammation in the lungs. If left untreated, this can lead to a condition known as bronchiectasis, which causes the widening of the lung airways. Additionally, bronchiectasis may result in lung scarring.
Symptoms of ABPA
The symptoms of ABPA may not be immediately apparent. People with asthma may experience flares (sudden increase in the symptoms). ABPA symptoms include:
- Wheezing
- Cough
- Shortness of breath
- Chest pain or tightness
- Cough with bloody mucus
- On and off fever (recurrent fevers)
- Fatigue
Diagnosis of ABPA
There are a number of diagnostic tests that a physician may order if they suspect that a patient may have ABPA. The diagnosis is based on the patient's symptoms and the results of the following tests:
- Allergy panel:
- Skin test: A few droplets of aspergillus (antigen) are dropped onto the skin and gently scratched, allowing these droplets to enter the skin. Within 10–15 minutes of exposure, a skin reaction may occur if the patient has an allergy to ABPA.
- Total IgE blood test: The levels of total IgE antibodies are measured in the blood sample. Elevated levels of IgE antibodies may occur if the patient has any type of allergy.
- Specific IgE blood test: The levels of specific IgE antibodies against Aspergillus are measured in the blood sample. Elevated levels of specific IgE antibodies against Aspergillus may occur if the patient has an ABPA allergy.
- Aspergillus IgG antibody test: The levels of Aspergillus IgG antibodies are measured in the blood sample. Elevated levels of Aspergillus IgG antibodies may occur in the case of a past ABPA infection.
- Sputum culture: This test is done to check if Aspergillus is growing in the respiratory airway. In the majority of individuals, Aspergillus will be present in the respiratory tract secretions (sputum), but they will not have ABPA. Conversely, an individual may still have ABPA even if the culture results are negative.
- CT (computed tomography): This scan provides a more comprehensive examination of the lungs and plays a vital role in the diagnosis of ABPA. The presence of central bronchiectasis combined with mucus impaction and centrilobular nodules is strongly associated with ABPA infection.
Interpretation of the results:
Positive test result:
A positive test result may be indicative of an ABPA infection. Sometimes the results may also show a false-positive result, especially in blood and sputum tests. A false-positive result indicates an ABPA infection even though the individual does not have ABPA. In the event of a false-positive, your healthcare provider may recommend further diagnostic tests.
Negative test result:
A negative test result means that an individual does not have an ABPA infection. Sometimes the results may also show a false-negative result, especially in blood and sputum tests. A false-negative result indicates the absence of ABPA infection even though the individual has ABPA.
Treatment of ABPA
The primary objective of treatment for ABPA is to manage inflammation and reduce the risk of further damage to the lungs. Generally, ABPA is treated in combination with oral corticosteroids and antifungal medicines.
Corticosteroids are used to manage inflammation and suppress the allergic response. Generally, individuals with ABPA are placed on oral corticosteroid treatment for a few months.
Antifungal drugs are the second form of treatment. These drugs help kill Aspergillus so that it no longer colonizes the airways. Most of these drugs are given for a minimum of 3–6 months. This treatment is effective in reducing fungal load and inflammatory activity.
Most of the time, individuals will improve with therapy, and their illnesses will go into remission. During remission, individuals will be asymptomatic, their asthma will be controlled, and they will have no new radiology scan findings or elevated IgE levels for at least six months. However, there may be repeated flare-ups of ABPA that may require additional treatment.
A combination of CT scans, lung function tests, and blood tests will be used to assess the effectiveness of the treatment. Healthcare providers will help individuals determine how long treatment should be continued, inform them about side effects from medicines, and plan for follow-up visits.
ABPA-related complications can be prevented by avoiding activities that involve close contact with soil or dust, such as yard work or gardening. If that isn't possible, wear a mask, shoes, and a long-sleeved shirt while working on outdoor activities such as gardening or visiting wooded areas. Allergy panel tests and radiology scans help in determining whether individuals have an ABPA infection, and early detection enables early treatment. Therefore, getting an allergy panel done is advised to avoid various ABPA flare-ups.
