Aspergillosis

Aspergillosis: A Spectrum of Fungal Infections

~Introduction

Aspergillosis is a group of diseases caused by fungi of the genus Aspergillus. These ubiquitous molds are found in soil, decaying vegetation, dust, and indoor environments. While most people inhale Aspergillus spores daily without ill effects, in certain individuals—especially those with weakened immune systems, underlying lung disease, or allergic tendencies—these fungi can cause a range of clinical syndromes.

Aspergillosis can be:

• Allergic – causing hypersensitivity reactions in the airways.

• Chronic – slowly progressive lung damage in structurally abnormal lungs.

• Invasive – rapidly progressive, life-threatening infection in immunocompromised patients.

---

~The Causative Organisms

The most common species causing human disease is:

• Aspergillus fumigatus – accounts for the majority of invasive infections.

Other species include:

• Aspergillus flavus

• Aspergillus niger

• Aspergillus terreus

• Aspergillus nidulans

These fungi produce small airborne conidia (spores) that can be inhaled deep into the lungs.

---

~Epidemiology

• Aspergillus species are widely distributed worldwide.

• Infections occur more commonly in:

  • Patients with prolonged neutropenia

  • Hematopoietic stem cell or solid organ transplant recipients

  • Individuals on long-term corticosteroids or immunosuppressants

  • Those with pre-existing lung diseases (e.g., tuberculosis, COPD, cystic fibrosis)

• Allergic bronchopulmonary aspergillosis (ABPA) is more common in asthmatics and cystic fibrosis patients.

---

~Pathogenesis

1. Inhalation of spores – Aspergillus conidia are inhaled into the alveoli.

2. Immune response – In healthy individuals, alveolar macrophages and neutrophils destroy spores.

3. Disease development – In certain settings:

   • Allergic reaction to spores → ABPA.

   • Growth in lung cavities → aspergilloma.

   • Invasion of lung tissue and blood vessels → invasive aspergillosis.

---

~Types of Aspergillosis

1. Allergic Bronchopulmonary Aspergillosis (ABPA)

• Cause: Hypersensitivity to Aspergillus antigens.

  
  
  

• Risk groups: Asthma, cystic fibrosis.

• Symptoms:

  • Wheezing, cough with mucus plugs.

  • Recurrent asthma exacerbations.

  • Fever, malaise.

• Complications: Bronchiectasis, progressive lung damage.

2. Aspergilloma (Fungal Ball)

• Cause: Colonization of pre-existing lung cavities (from TB, sarcoidosis, or other diseases).

• Appearance: A mass of fungal hyphae, mucus, and cellular debris inside the cavity.

• Symptoms:

  • Often asymptomatic.

  • Hemoptysis (coughing up blood) is common and can be severe.

3. Chronic Pulmonary Aspergillosis (CPA)

• Cause: Slowly progressive infection in patients with chronic lung disease.

• Symptoms: Weight loss, cough, fatigue, mild fever, hemoptysis.

• Course: Can persist for months to years.

4. Invasive Aspergillosis

• Cause: Aggressive infection in severely immunocompromised patients.

• Sites involved: Lungs primarily; may spread to brain, kidneys, skin.

• Symptoms:

  • Fever unresponsive to antibiotics.

  • Cough, chest pain, hemoptysis.

  • Shortness of breath.

• Prognosis: High mortality if untreated.

5. Cutaneous Aspergillosis

• Primary: Direct inoculation into skin (e.g., at catheter site, burn wound).

• Secondary: From hematogenous spread in disseminated infection.

---

~Clinical Features Summary Table

Form of Aspergillosis	Key Risk Groups	Main Symptoms	Disease Course
ABPA	Asthma, cystic fibrosis	Wheezing, cough, mucus plugs	Relapsing-remitting
Aspergilloma	Prior lung cavities	Hemoptysis	Usually stable, may bleed
CPA	Chronic lung disease	Cough, weight loss, fatigue	Slowly progressive
Invasive	Immunocompromised	Fever, cough, chest pain, dyspnea	Rapidly progressive, high mortality
Cutaneous	Burns, wounds	Red nodules, ulceration	Local or systemic spread

---

~Diagnosis

Diagnosis varies by form but generally includes:

1. Imaging

• Chest X-ray / CT scan:

  • Aspergilloma: Cavitary lesion with a mobile intracavitary mass and air crescent.

  • Invasive disease: Nodules, halo sign (CT), cavitation.

2. Microbiological Tests

• Sputum or bronchoalveolar lavage for fungal culture and microscopy.

• Staining may reveal septate hyphae with acute-angle branching.

3. Serology and Antigen Tests

• IgE & IgG antibodies to Aspergillus (ABPA and CPA).

• Galactomannan antigen – useful in invasive aspergillosis.

• β-D-glucan – non-specific fungal marker.

4. Histopathology

• Demonstration of hyphae invading tissue in invasive disease.

---

~Treatment

1. Allergic Bronchopulmonary Aspergillosis

• Oral corticosteroids (prednisone).

• Antifungal agents (itraconazole, voriconazole) to reduce fungal burden.

2. Aspergilloma

• Asymptomatic: Observation.

• Symptomatic with hemoptysis: Surgical resection if feasible.

• Antifungals may be used in inoperable cases.

3. Chronic Pulmonary Aspergillosis

• Long-term oral triazoles (itraconazole, voriconazole).

• Treatment often for 6–12 months or longer.

4. Invasive Aspergillosis

• First-line: Voriconazole (oral or IV).

• Alternatives: Isavuconazole, liposomal amphotericin B.

• Early initiation is critical; delay increases mortality.

• Address underlying immunosuppression if possible.

5. Cutaneous Aspergillosis

• Local debridement + systemic antifungal therapy.

---

~Prevention

• Hospital settings: HEPA filtration in rooms for high-risk patients.

• Avoid construction areas for immunocompromised individuals.

• General: Reduce exposure to dusty environments and decaying vegetation if immunosuppressed.

• Prophylactic antifungal medication in high-risk transplant patients.

---

~Prognosis

• ABPA: Good with early treatment; risk of chronic lung damage if untreated.

• Aspergilloma: Variable; risk of fatal hemoptysis.

• CPA: Chronic course, requires long-term therapy.

• Invasive: Mortality rates can exceed 50%, especially with delayed diagnosis.

---

~Public Health Importance

Aspergillosis is a significant opportunistic infection in the era of advanced medical care due to increased numbers of immunocompromised patients. Awareness, rapid diagnosis, and timely treatment are essential to improve survival. Surveillance and preventive strategies in hospitals can reduce nosocomial cases, particularly in transplant and oncology wards.

---

~Conclusion

Aspergillosis represents a spectrum of diseases ranging from mild allergic conditions to aggressive, life-threatening infections. While Aspergillus spores are an unavoidable part of the environment, disease occurs when host defenses fail or hypersensitivity develops. Clinicians must maintain a high index of suspicion in at-risk patients, as early diagnosis and treatment dramatically improve outcomes.