Your asthma medications are not working. You are coughing up thick, brownish mucus. Your doctor has tried multiple inhalers, but your symptoms keep getting worse. The problem may not be asthma alone. You could have allergic bronchopulmonary aspergillosis (ABPA) — an immune reaction to a common mold called Aspergillus fumigatus that can masquerade as severe asthma and cause permanent lung damage if it goes undiagnosed.
Important: ABPA is estimated to affect 1–2% of all asthma patients and up to 13% of those with difficult-to-control asthma. South Florida’s warm, humid climate creates ideal conditions for Aspergillus mold growth, making awareness especially important for patients in Plantation, Fort Lauderdale, and Broward County.
What Is ABPA?
Allergic bronchopulmonary aspergillosis is not an infection in the traditional sense. It is a hypersensitivity reaction — your immune system overreacts to Aspergillus fungal spores that colonize the mucus in your airways. The result is a cascade of inflammation that goes far beyond typical allergic asthma:
- Aspergillus spores are inhaled. These microscopic spores are ubiquitous in the environment — in soil, decaying vegetation, air conditioning systems, and damp indoor spaces.
- The fungus colonizes bronchial mucus. In most people, the immune system clears the spores without issue. In susceptible asthma patients, the fungus takes hold in the thick mucus of inflamed airways.
- An exaggerated immune response develops. The body produces massive amounts of IgE antibodies (both total and Aspergillus-specific), activates eosinophils, and triggers a Th2 inflammatory response.
- Chronic inflammation damages the airways. Repeated cycles of inflammation, mucus plugging, and immune activation lead to bronchiectasis (permanent widening and scarring of the airways), particularly in the central bronchi.
Without treatment, ABPA can progress through stages of increasing severity, ultimately causing pulmonary fibrosis (irreversible lung scarring) and significant loss of lung function.
Who Is at Risk?
ABPA overwhelmingly affects two groups of patients:
- People with asthma — especially moderate-to-severe or difficult-to-control asthma
- People with cystic fibrosis — up to 15% of CF patients develop ABPA
Additional Risk Factors
| Risk Factor | Why It Matters |
|---|---|
| Atopic predisposition | History of allergies, eczema, or allergic rhinitis indicates a Th2-dominant immune profile |
| Aspergillus sensitization | Positive skin prick test or elevated Aspergillus-specific IgE is a prerequisite |
| Genetic factors | HLA-DR2 and HLA-DR5 genotypes increase susceptibility; CFTR gene variants (even without CF) may also contribute |
| Hot, humid climate | South Florida’s subtropical environment promotes Aspergillus growth in both outdoor and indoor settings |
| Indoor mold exposure | Water-damaged buildings, poor ventilation, and older HVAC systems can harbor high Aspergillus concentrations |
| Oral corticosteroid use | Paradoxically, systemic steroids (while treating ABPA) can also promote fungal colonization |
Symptoms: How ABPA Differs from Typical Asthma
ABPA can be difficult to distinguish from severe eosinophilic asthma because many symptoms overlap. However, several features should raise suspicion:
| Feature | Typical Severe Asthma | ABPA |
|---|---|---|
| Response to inhalers | Partial to good response | Poor or declining response despite escalating therapy |
| Sputum character | Clear to white | Thick, brownish-black mucus plugs (sometimes forming bronchial casts) |
| Fever | Usually absent unless infection | Low-grade fever during flares |
| Weight loss / malaise | Not typical | May occur, especially during acute exacerbations |
| Chest X-ray | Often normal or hyperinflation | Fleeting pulmonary infiltrates, mucoid impaction, central bronchiectasis |
| Total IgE | May be mildly elevated | Markedly elevated (>1,000 IU/mL, often >2,000) |
| Blood eosinophils | May be elevated | Usually >500 cells/μL, often >1,000 |
| Aspergillus-specific IgE | Negative or low | Strongly positive |
| Course over time | Relatively stable with treatment | Relapsing-remitting; flares with new infiltrates |
Red flag: If you are coughing up brown or dark mucus plugs and your asthma is getting worse despite maximum inhaler therapy, ask your doctor about ABPA testing. Early detection prevents irreversible lung damage.
The Five Stages of ABPA
ABPA was classically described in five stages, though patients do not always progress linearly through them:
| Stage | Name | Features |
|---|---|---|
| I | Acute | Pulmonary infiltrates, elevated total IgE, eosinophilia, positive Aspergillus skin test |
| II | Remission | Symptoms resolve (often with corticosteroid treatment); IgE may remain elevated but stable |
| III | Exacerbation | Recurrence of symptoms and infiltrates; IgE rises ≥100% above baseline |
| IV | Corticosteroid-dependent | Requires ongoing systemic steroids to maintain control; early bronchiectasis may develop |
| V | Fibrotic (end-stage) | Irreversible pulmonary fibrosis, extensive bronchiectasis, permanent loss of lung function |
The goal of treatment is to keep patients in Stage II (remission) and prevent progression to Stages IV and V.
How ABPA Is Diagnosed
Diagnosis requires a combination of clinical, laboratory, and imaging findings. At Advanced Asthma Clinic, Dr. Frank Hull uses a systematic approach based on the modified Rosenberg-Patterson criteria and the more recent ISHAM (International Society for Human and Animal Mycology) working group guidelines:
Essential Diagnostic Criteria
- Predisposing condition: Asthma or cystic fibrosis
- Aspergillus sensitization: Positive skin prick test to A. fumigatus OR elevated Aspergillus-specific IgE (>0.35 kUA/L)
- Elevated total serum IgE: ≥1,000 IU/mL (during active disease)
Supporting Criteria (at least two of the following)
- Elevated Aspergillus-specific IgG (precipitins)
- Radiographic findings consistent with ABPA (fleeting infiltrates, mucoid impaction, central bronchiectasis)
- Peripheral blood eosinophilia (>500 cells/μL) in patients not on systemic corticosteroids
Diagnostic Workup at Our Clinic
- Spirometry and lung function testing — to establish baseline airflow obstruction and monitor changes
- Complete blood count (CBC) — to check eosinophil levels
- Total serum IgE — the single most important screening and monitoring test
- Aspergillus-specific IgE and IgG — to confirm sensitization and immune response
- Chest X-ray and/or high-resolution CT (HRCT) — to identify infiltrates, mucoid impaction, and central bronchiectasis
- Fractional exhaled nitric oxide (FeNO) — typically elevated, reflecting eosinophilic airway inflammation
- Sputum culture — may grow Aspergillus, though a negative culture does not exclude ABPA
With over 20 years of experience in pulmonary medicine and clinical research, Dr. Hull recognizes that ABPA is frequently missed in patients labeled as having “difficult asthma.” A thorough evaluation can uncover this treatable condition and change a patient’s trajectory.
ABPA Classification: ABPA-S vs. ABPA-CB
ABPA is further classified based on the presence or absence of bronchiectasis:
- ABPA-S (serological ABPA): All serological criteria are met, but CT imaging does not show bronchiectasis. This is the earlier, more treatable form.
- ABPA-CB (ABPA with central bronchiectasis): CT reveals bronchiectasis predominantly in the central two-thirds of the lungs. This represents more advanced disease with structural airway damage.
Identifying ABPA at the ABPA-S stage — before bronchiectasis develops — offers the best opportunity to prevent permanent lung damage.
Treatment of ABPA
Treatment targets both the immune overreaction and the fungal burden in the airways:
1. Oral Corticosteroids
Systemic corticosteroids (typically prednisone) remain the cornerstone of ABPA treatment during acute flares. A standard regimen involves:
- Prednisone 0.5 mg/kg/day for 2 weeks
- Gradual taper over 3–5 months
- Monitoring total IgE every 6–8 weeks during taper
Corticosteroids suppress the inflammatory cascade, resolve pulmonary infiltrates, improve symptoms, and lower total IgE. However, long-term steroid use carries significant side effects, driving the need for steroid-sparing strategies.
2. Antifungal Therapy
Itraconazole is the most widely used antifungal for ABPA. By reducing the Aspergillus fungal load in the airways, it decreases the antigenic stimulus driving the immune reaction. Typical use:
- Itraconazole 200 mg twice daily for 16 weeks (as adjunct to steroids)
- Monitor itraconazole blood levels (therapeutic drug monitoring) to ensure adequate absorption
- Liver function tests at baseline and periodically during treatment
Voriconazole is an alternative for patients who do not respond to or cannot tolerate itraconazole.
3. Biologic Therapies
For patients with corticosteroid-dependent ABPA or frequent relapses, biologic medications offer promising steroid-sparing options:
- Omalizumab (Xolair) — an anti-IgE monoclonal antibody that directly targets the elevated IgE driving ABPA. Multiple case series and small trials show reduced exacerbations and steroid requirements.
- Dupilumab (Dupixent) — targets IL-4 and IL-13, key cytokines in the Th2 response. Emerging evidence shows benefit in refractory ABPA.
- Mepolizumab and benralizumab — anti-IL-5 pathway biologics that reduce eosinophils. May benefit ABPA patients with marked eosinophilia.
Dr. Hull has extensive experience with biologic therapies for severe asthma and evaluates each patient for the most appropriate option based on their individual immunological profile.
4. Ongoing Asthma Management
ABPA treatment works alongside — not instead of — standard asthma management:
- Personalized asthma action plans
- Inhaled corticosteroids and long-acting bronchodilators
- Mold avoidance strategies to reduce ongoing Aspergillus exposure
- Regular lung function monitoring
Long-Term Monitoring
ABPA is a relapsing condition. Even after successful treatment, lifelong monitoring is recommended:
- Total IgE every 3–6 months — a doubling of baseline IgE may signal relapse before symptoms appear
- Annual chest imaging — to detect new infiltrates or progressive bronchiectasis
- Spirometry every 6–12 months — to track lung function trends
- Symptom diaries — tracking sputum color, volume, and character can provide early warning
ABPA and South Florida: A Regional Concern
Aspergillus fumigatus thrives in warm, humid environments. South Florida’s climate — with year-round temperatures above 70°F and high humidity — creates a particularly favorable habitat. Common local exposure sources include:
- Outdoor: Decomposing vegetation, mulch, compost piles, construction sites
- Indoor: HVAC systems (especially if poorly maintained), water-damaged drywall, bathroom mold, window condensation
- After hurricanes or flooding: Massive increases in indoor mold — multiple studies have documented ABPA flares after major storm events in Florida
For practical strategies to reduce mold exposure, see our guide on asthma and mold.
When to See a Specialist
Consider evaluation for ABPA if you experience any of the following:
- Asthma that keeps getting worse despite multiple medications
- Coughing up brown, dark, or unusually thick mucus
- Recurrent “pneumonias” or chest X-ray abnormalities
- History of Aspergillus allergy on skin or blood testing
- Unexplained weight loss, fatigue, or low-grade fevers alongside asthma
- Total IgE >500 IU/mL without clear explanation
Early diagnosis and treatment can prevent irreversible lung damage. Contact Advanced Asthma Clinic at (954) 522-7226 to schedule a comprehensive evaluation with Dr. Frank Hull.
Related Resources
Medical disclaimer: This article is for educational purposes and does not replace professional medical advice. ABPA requires specialized testing and treatment. Always consult your physician before making changes to your asthma management. If you are experiencing worsening breathing symptoms, contact your healthcare provider or call 911 for emergencies.