Chronic Hypersensitivity Pneumonitis (cHP)

cHP results from repeated inhalation of organic antigens leading to immune-mediated lung inflammation and fibrosis. Common sources include birds, mold, hot tubs, farming, and contaminated ventilation systems. Early antigen avoidance is critical to prevent irreversible lung damage.

Symptoms

• Chronic cough, dyspnea on exertion
• Fatigue, weight loss, low-grade fevers
• Inspiratory crackles, digital clubbing in advanced fibrosis

Diagnosis

• Detailed environmental exposure history
• HRCT: mosaic attenuation/air trapping, centrilobular nodules, reticulation, honeycombing (fibrotic)
• BAL: lymphocytosis (>20–30%)
• Lung biopsy (transbronchial cryobiopsy or surgical) if diagnosis uncertain
• Serum precipitins (specific IgG) supportive but not definitive
• PFTs: restrictive with reduced DLCO; air trapping (increased RV) in some cases

Management

Antigen Identification & Avoidance

• Environmental assessment (home/work), professional remediation, relocation if necessary
• Wear respirators or PPE if ongoing exposure unavoidable

Pharmacologic Therapy

• Corticosteroids for acute/subacute inflammation; taper to lowest effective dose
• Steroid-sparing agents: mycophenolate, azathioprine, rituximab for chronic inflammatory phenotype
• Antifibrotic therapy (nintedanib, pirfenidone) for progressive fibrosing cHP
• Treat airflow obstruction with bronchodilators if present

Supportive Care

• Pulmonary rehabilitation, exercise training
• Vaccinations (influenza, COVID-19, pneumococcal, RSV if eligible)
• Oxygen therapy for resting or exertional hypoxemia
• Manage comorbid GERD, sleep apnea, pulmonary hypertension

Advanced Disease

• Lung transplant evaluation for progressive fibrosis despite therapy

Living with cHP

• Track exposures, symptoms, PFTs, imaging, medications, oxygen saturation, and rehab sessions
• Maintain indoor humidity <50%, use HEPA filters, clean HVAC systems
• Engage occupational/environmental medicine specialists
• Mental health support; relocation/job changes are stressful

Complications

• Progressive pulmonary fibrosis, respiratory failure
• Pulmonary hypertension
• Acute exacerbations triggered by re-exposure or infection

Research & Future Directions

Biomarkers predicting treatment response, microbiome shifts, and immune modulation strategies are under study.

Experimental & Emerging Treatments

• Precision Antifibrotic Combinations: Trials pairing antifibrotics with immunosuppressants.
• B-cell Targeting (rituximab): For steroid-refractory inflammatory cHP.
• Digital Environmental Sensors: Detect airborne antigens/mold spores to warn patients.
• Mesenchymal Stem Cell Therapy: Investigated to reduce fibrosis and inflammation.

Track cHP with Diagnoza.care

Link Symptoms to Environments – Log exposures, humidity/air quality readings, PFTs, HRCT results, medications, oxygen use, rehab sessions, and lung transplant milestones; capture side effects; and let the AI companion highlight exposure-symptom correlations and progression trends.

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Medical Disclaimer: Informational only. Partner with your ILD pulmonologist and environmental specialists for antigen identification, immunosuppression, and transplant planning. Sources: American Thoracic Society, European Respiratory Society, CHEST Guidelines on Hypersensitivity Pneumonitis