What is Allergic Bronchopulmonary Aspergillosis?
Allergic bronchopulmonary aspergillosis (ABPA) is an infection in the lungs, usually caused by an overreaction of the immune system to the antigens of a specific type of fungus, Aspergillus fumigatus. This usually happens when this fungus colonizes the airways. This mainly affects people with bronchial asthma and cystic fibrosis, two conditions that affect the respiratory system. Symptoms of ABPA can include trouble breathing, changes in the lungs that show up on scans, an increase in a type of white blood cell called eosinophils, and signs that the body is reacting to the antigens of the Aspergillus species, showing that there’s an allergic reaction happening.
What Causes Allergic Bronchopulmonary Aspergillosis?
Aspergillus is a type of mold that is found everywhere in our surroundings, especially in organic matter. There are over 100 different types of Aspergillus across the globe, but most illnesses are caused by a few specific types: Aspergillus fumigatus, Aspergillus niger, Aspergillus flavus, and Aspergillus clavatus. Depending on a person’s immune system, an infection by Aspergillus can result in a variety of illnesses, from allergic reactions to infections that spread through your blood vessels.
In particular, Aspergillus fumigatus is a common airborne fungus that most often leads to a condition called ABPA. The fungal spores, which are very small (around 2 to 3 micrometers in size), can easily reach the lungs and settle there.
ABPA is a condition most often seen in people with asthma or cystic fibrosis who are allergic to Aspergillus. People with these conditions have a hard time getting rid of the Aspergillus spores when they inhale them because they have thick mucus in their air passages. The disease also seems to have a genetic link: certain types of HLA-DR molecules (like DR2, DR5, and maybe DR4 or DR7) seem to increase a person’s risk of developing ABPA. On the other hand, a molecule called HLA-DQ2 appears to help protect against it. Researchers believe that a person’s mix of these molecules might help determine their risk of getting ABPA if they have cystic fibrosis or asthma.
Risk Factors and Frequency for Allergic Bronchopulmonary Aspergillosis
Allergic bronchopulmonary aspergillosis, or ABPA for short, often shows up from the age of 30 to 50, but it’s also frequently found in children. This condition usually impacts those with severe asthma and cystic fibrosis. Interestingly, about a quarter of those with asthma and half of those with cystic fibrosis test positive for Aspergillus allergies. However, not everyone with these allergies get ABPA — only about 13% of asthmatics and 9% of cystic fibrosis patients get it. Globally, more than 4 million people have ABPA.
- ABPA typically shows up in people aged 30 to 50 and in children.
- It’s usually found in those with severe asthma and cystic fibrosis.
- About 25% of people with asthma and 50% of people with cystic fibrosis have an allergy to Aspergillus.
- Among those with these allergies, about 13% of asthmatics and 9% of cystic fibrosis patients will develop ABPA.
- Worldwide, ABPA affects more than 4 million people.
The main trigger for ABPA is a fungus called A. fumigatus, which thrives on dead organic matter. The highest number of infections occur in the winter because fallen leaves provide the fungus with the environment it needs to grow.
Signs and Symptoms of Allergic Bronchopulmonary Aspergillosis
Allergic bronchopulmonary aspergillosis, commonly known as ABPA, primarily affects people with asthma or cystic fibrosis. It’s characterized by certain symptoms and histories that can help in its identification.
- History of recurrent wheezing episodes and lung changes seen in X-rays, including temporary patchy infiltrates and bronchiectasis. However, not all patients may exhibit wheezing, and some may present with lung consolidation even without any symptoms.
- Experiences of uncontrolled asthma that gets worse even when taking optimal medication.
- A history of cystic fibrosis.
- Symptoms such as cough, difficulty breathing, chest pain that worsens with deep breaths, coughing up blood-stained spit or spit with brown mucus plugs.
- General complaints such as loss of appetite, tiredness, body pain, low-grade fever, and weight loss.
- ABPA may occur alongside allergic fungal sinusitis, presenting symptoms of long-term sinusitis with pus-filled sinus discharge.
During the physical examination, the doctor may notice:
- Wheezing and/or rhonchi (continuous, low-pitched rattling sounds) when listening to the chest of patients with asthma who have ABPA.
- Crepitations (crackling sounds) during chest auscultation in patients with cystic fibrosis who have ABPA, due to bronchiectasis, a condition where the bronchial tubes in the lungs are permanently damaged and widened.
- Rapid breathing, possibly due to an asthma flare-up or a secondary lung infection.
Testing for Allergic Bronchopulmonary Aspergillosis
Allergic bronchopulmonary aspergillosis (ABPA) can’t be diagnosed with a single test. Instead, doctors use a combination of symptoms, x-rays, and lab tests to diagnose this condition.
One common test used to diagnosis sensitivity to A. fumigatus, a fungus, is the Aspergillus skin test. This test checks if the skin reacts to the fungus, indicating that the patient’s body has built up specific antibodies against it, which is characteristic of ABPA.
Blood tests can also help with the diagnosis. These can show high levels of a type of immune protein (IgE), particularly against A. fumigatus, the presence of a certain type of white blood cell (eosinophils), and whether the blood reacts to the fungus.
A chest X-ray which can show lung damage or inflammation could indicate ABPA. More specific tests such as a High-resolution computed tomography (HRCT) scan can give doctors a more detailed image of the lungs. The scan can reveal inflammation or conditions such as bronchiectasis, which is widening and damage of the airways, or “bronchi”. It can point out conditions that are missed on an X-ray, giving doctors a clearer picture of what’s happening in the lungs.
Other types of tests that your doctor might use include pulmonary function tests, which measure how well your lungs are working, and a bronchoscopy, which allows the doctor to look directly into the lungs.
Using the combination of these tests and the symptoms a patient is experiencing, medical professionals follow a set of criteria to diagnose and categorize ABPA. It’s important to note that patients who have cystic fibrosis, a genetic disorder that damages the lungs, are also at risk of developing ABPA. In these cases, some symptoms may be different or more difficult to diagnose, and doctors will use slightly different criteria to make their diagnosis.
When treating ABPA in patients with cystic fibrosis, if new symptoms, new x-ray findings, or an increase in IgE levels is observed, treatment should be initiated right away.
Treatment Options for Allergic Bronchopulmonary Aspergillosis
The primary goal of treating allergic bronchopulmonary aspergillosis (a condition where the fungus Aspergillus infects the lungs and causes inflammation) is to get control over bouts of intense inflammation and to prevent further lung damage.
The key objectives of the treatment are:
• Making symptoms better
• Preventing episodes of severe symptoms
• Preserving normal lung function
Various medications are useful for treating this condition:
• Anti-inflammatory drugs: Steroids such as Prednisolone are frequently used because they help to relieve symptoms, reduce inflammation in the lungs, and prevent permanent lung damage.
• Antifungal drugs: These drugs decrease the amount of fungal spores in the body, reducing inflammation and perhaps leading to fewer episodes of severe symptoms.
• Anti IgE therapy: These drugs limit the body’s allergic response, which can reduce inflammation and other symptoms.
• Antibiotics: These can help to prevent or treat potential bacterial infections that might occur alongside the fungal infection.
How often your doctor checks your IgE levels (the main antibodies involved in allergies) will depend on the severity of your condition, but it’s typical to do a follow-up every two months or shortly after a severe episode to see how the treatment is going.
A medication called Itraconazole is a commonly used antifungal agent. It helps to significantly reduce steroid dose, lowers IgE levels, resolves lung inflammation, improves exercise tolerance, and enhances lung function.
In some cases, when steroids can’t be used or they aren’t enough to manage the condition, a medication called Omalizumab may be used. This medication prevents a specific type of reaction that can lead to inflammation.
Alongside these treatments, physicians may also suggest supportive measures to help manage the condition. These might include techniques to clear the airways in patients with a specific form of lung damage (bronchiectasis) associated with the condition, and avoiding environments with high fungus counts to prevent further exposure and flare-ups.
What else can Allergic Bronchopulmonary Aspergillosis be?
Allergic bronchopulmonary aspergillosis, also known as ABPA, can mimic many other diseases that affect the airway and lungs. This can make it difficult to diagnose because it might look like other conditions such as undiagnosed lung issues, pneumonia, and bronchiectasis. Here are some diseases that doctors need to consider and rule out when trying to diagnose ABPA:
- Asthma that requires corticosteroids for treatment, but is not ABPA
- Severe asthma with fungal sensitivity (SAFS)
- Cystic fibrosis (CF)
- Bronchiectasis
- Chronic necrotizing aspergillosis
- Chronic eosinophilic pneumonia
- Chronic obstructive pulmonary disease (COPD)
- Churg–Strauss syndrome
- Bronchocentric granulomatosis
- Acute eosinophilic pneumonia (including drug-induced pneumonitis)
- Pulmonary tuberculosis
- Parasitic infections
- Hypersensitivity pneumonitis
What to expect with Allergic Bronchopulmonary Aspergillosis
The course and pattern of ABPA (Allergic Bronchopulmonary Aspergillosis), including its development, improvement, and relapses, are not fully understood. However, patients who did not have central bronchiectasis (damage to the airways in the lungs) at the time of diagnosis usually manage to maintain their lung function despite occasional flare-ups. With proper treatment, ABPA can be controlled in the long term and full recovery is common.
Treating early-stage ABPA with corticosteroids can typically lead to reduced coughing up of phlegm, better control of airway constriction, and a decrease in IgE (a type of immune protein that increases during allergy) levels by over 35% within eight weeks. This treatment can also clear up antibodies that cause disease and improve lung imaging results. Although IgE levels usually do not return to normal completely, they could decrease by about half from the levels seen during the peak of the disease.
Progression to lung scarring in advanced-stage ABPA might be stopped if patients stay on a treatment plan involving low-dose steroids. Patients with a FEV1 (a measure of lung function) consistently below 0.8 L typically have a worse outlook.
Possible Complications When Diagnosed with Allergic Bronchopulmonary Aspergillosis
Allergic bronchopulmonary aspergillosis can lead to several complications such as:
- Repeated asthma flare-ups and reliance on steroids
- Aspergilloma, a fungal ball formed by Aspergillus fungi
- Invasive aspergillosis, a serious condition where the fungi infects the organs
- Chronic pulmonary aspergillosis, a long-term lung condition
- Cavitation, or the formation of cavities in the lung
- Local emphysema, a lung condition that causes shortness of breath
- Chronic or repeated collapse of a part of the lung (lobar atelectasis)
- Honeycomb fibrosis, a severe condition where the lungs develop a honeycomb-like appearance
- Complications from bronchiectasis such as coughing up blood (hemoptysis) and repeated lung infections
Preventing Allergic Bronchopulmonary Aspergillosis
If you have allergic bronchopulmonary aspergillosis (a lung condition caused by an allergic reaction to a fungus known as aspergillus), it’s important to keep a close eye on your symptoms. If your breathing issues start to get worse, or if you notice new symptoms while receiving treatment for stage 2 or stage 3 of the condition, you should contact a lung specialist (pulmonologist) right away.
People with ABPA-CB, a stage of the condition where there is damage to the airways, have a higher odd of getting another infection and complications related to bronchiectasis (permanent enlargement of the airways). If you experience symptoms like fever or coughing up blood (hemoptysis), it’s crucial to consult a pulmonologist immediately.
If you’re taking oral corticosteroids for a long time (a type of medicine often used to reduce inflammation), make sure you understand the possible side effects. These medications can sometimes cause thinning or weakening of the bones (osteoporosis/osteopenia) or clouding of the lens in your eye (cataracts). To catch these issues early, screenings, including bone density measurements and eye exams, should be done regularly.
If you have bronchiectasis, it’s helpful to learn techniques to clear your lungs of thick mucus (sputum). Also, it’s recommended to get flu and pneumonia vaccines to help prevent further damage to the lungs.
Try to avoid places or situations where you might be exposed to high amounts of mold, such as compost piles or moldy indoor areas. These can potentially provoke a negative response from your immune system.
