Fungal Lung Infections

Definition | Aetiology | Pathophysiology | Risk Factors | Signs and Symptoms | Investigations | Management | Referral

Definition

Fungal lung infections are caused by the inhalation of fungal spores, leading to respiratory symptoms and pulmonary disease. They can range from mild infections in immunocompetent individuals to severe, life-threatening infections in immunocompromised patients.

Aetiology

Common fungal pathogens causing lung infections include:

  • Aspergillus species: this causes invasive aspergillosis or chronic pulmonary aspergillosis.
  • Pneumocystis jirovecii: this is a major cause of pneumonia in immunocompromised patients, particularly those with HIV/AIDS.
  • Histoplasma capsulatum: this causes histoplasmosis, endemic to certain regions.
  • Coccidioides species: this causes coccidioidomycosis, often seen in endemic areas.
  • Cryptococcus neoformans: this can cause pulmonary cryptococcosis, often seen in HIV-positive patients.

Pathophysiology

Fungal spores are inhaled and deposited in the lungs, leading to:

  • Activation of the immune response, causing inflammation and granuloma formation.
  • Progressive lung damage in immunocompromised individuals.
  • Dissemination of infection in severe cases, affecting other organs.

Risk factors

  • Immunosuppression (e.g., HIV/AIDS, chemotherapy, corticosteroids).
  • Organ transplantation or long-term immunosuppressive therapy.
  • Chronic lung disease (e.g., COPD, bronchiectasis).
  • Exposure to fungal spores in endemic areas.

Signs and symptoms

  • Fever, cough, haemoptysis.
  • Pleuritic chest pain.
  • Severe respiratory distress in advanced cases.
  • Progressive dyspnoea.
  • Dry cough.
  • Hypoxaemia that worsens on exertion.
  • Weight loss, fatigue.
  • Chronic cough with or without haemoptysis.

Investigations

  • Chest X-ray: may show areas of shadowing suggestive of infection.
  • CT or MRI scan: used for detailed imaging if further assessment is needed.
  • Blood cultures: can detect fungal growth in the bloodstream.
  • Sputum sample: analysed in the lab to identify fungal pathogens.
  • Blood tests: may indicate an immune response to the infection.
  • Bronchoscopy: allows direct visualisation of the lungs and sampling for culture.

Management

  • This is done by a respiratory specialist.

Referral

Refer to secondary care in the following scenarios:

  • Respiratory Specialist: For diagnosis and management of chronic or invasive fungal infections.
  • Infectious Disease Specialist: For suspected disseminated fungal infections or multidrug-resistant cases.
  • Hospital admission:
    • Severe respiratory compromise or worsening hypoxaemia.
    • Immunocompromised patients with suspected invasive fungal disease.
 
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