◆

Subtypes

2

Recurrent chronic bird fancier's lung

Chronic BFL with recurrent acute episodes that progress to interstitial pulmonary fibrosis.

Show evidence (1 reference)

PMID:12839317 SUPPORT Human Clinical

"One subgroup of patients develops interstitial pulmonary fibrosis after recurrent acute episodes (recurrent BFL)"

The abstract defines a recurrent chronic BFL subtype marked by recurrent acute episodes and fibrotic progression.

Insidious chronic bird fancier's lung

Chronic BFL with slowly progressive respiratory disease without a history of acute episodes.

Show evidence (1 reference)

PMID:12839317 SUPPORT Human Clinical

"the other subgroup of patients has no history of acute episodes but has slowly progressive chronic respiratory disease (insidious BFL)."

The abstract defines an insidious subtype with slow progression and no acute episode history.

⚙

Pathophysiology

11

Exposure to Avian Proteins

Repeated inhalation of avian proteins from bird droppings, feathers, or serum triggers bird-related hypersensitivity pneumonitis.

lung UBERON:0002048

Downstream

Bird Antigen-Driven Humoral Response Repeated avian antigen exposure triggers measurable bird-specific antibody responses.

Th1/Th2 to Th2/Th17 Cytokine Shift Antigen exposure initiates the hypersensitivity-pneumonitis immune response that shifts across disease stages.

Dyspnea Immune-mediated interstitial lung disease from repeated avian antigen exposure clinically manifests with dyspnea.

Cough Immune-mediated interstitial lung disease from repeated avian antigen exposure clinically manifests with cough.

Show evidence (3 references)

DOI:10.3390/ijms24032884 SUPPORT Model Organism

"Bird-related hypersensitivity pneumonitis (BRHP) is an interstitial lung disease induced by avian proteins."

The review defines BRHP as an avian protein-induced interstitial lung disease.

PMID:39958101 SUPPORT Human Clinical

"Bird fancier's lung (BFL) is a subtype of hypersensitivity pneumonitis (HP), an immune-mediated interstitial lung disease (ILD) resulting from the repeated inhalation of avian proteins found in bird droppings, feathers, and serum."

The case report links BFL to repeated inhalation of avian proteins as the causative trigger for interstitial lung disease.

PMID:33318919 SUPPORT Human Clinical

"Bird Fancier's Lung is a type of hypersensitivity pneumonitis, an immunologically mediated lung disease due to repetitive exposure of air-borne avian antigen."

The report characterizes BFL as an immune-mediated interstitial lung disease driven by repetitive avian antigen exposure.

Expansion of Resident Monocytes and Interstitial Macrophages

Bird antigen exposure is associated with increased resident monocytes, interstitial macrophages, and type 2 dendritic cells in the lung.

monocyte CL:0000576 macrophage CL:0000235 dendritic cell CL:0000451

lung UBERON:0002048

Downstream

Th1/Th2 to Th2/Th17 Cytokine Shift Monocyte, macrophage, and dendritic-cell remodeling is modeled upstream of the stage-dependent T-cell cytokine shift.

Show evidence (1 reference)

DOI:10.3390/ijms24032884 SUPPORT Model Organism

"Both groups presented increases in resident monocytes, interstitial macrophages and type 2 dendritic cells (DCs), but also reductions in inflammatory monocytes, alveolar macrophages and tolerogenic DCs compared with their control groups."

The mouse model reports increased resident monocytes, interstitial macrophages, and type 2 dendritic cells after bird antigen exposure.

Reduction of Inflammatory Monocytes and Alveolar Macrophages

Bird antigen exposure is associated with reduced inflammatory monocytes, alveolar macrophages, and tolerogenic dendritic cells in the lung.

monocyte CL:0000576 macrophage CL:0000235 dendritic cell CL:0000451 alveolar macrophage CL:0000583

lung UBERON:0002048

Show evidence (1 reference)

DOI:10.3390/ijms24032884 SUPPORT Model Organism

"Both groups presented increases in resident monocytes, interstitial macrophages and type 2 dendritic cells (DCs), but also reductions in inflammatory monocytes, alveolar macrophages and tolerogenic DCs compared with their control groups."

The same experiment reports reduced inflammatory monocytes, alveolar macrophages, and tolerogenic dendritic cells.

Th1/Th2 to Th2/Th17 Cytokine Shift

Early disease shows a mixed Th1/Th2 response, while progression shifts toward a Th2/Th17 mixed response.

T cell CL:0000084

T cell activation GO:0042110

lung UBERON:0002048

Downstream

Fever Acute inflammatory hypersensitivity pneumonitis can produce flu-like systemic symptoms.

Fatigue Chronic inflammatory hypersensitivity pneumonitis can produce fatigue.

Dyspnea Lung inflammation and evolving interstitial injury produce exertional dyspnea.

Cough Lung inflammation from hypersensitivity pneumonitis produces cough.

Hypoxemia Active inflammatory interstitial lung disease can impair gas exchange.

Show evidence (1 reference)

DOI:10.3390/ijms24032884 SUPPORT Model Organism

"In the first stages of BRHP, there is a mixed Th1/Th2 immune response, while during the progression of the disease, although there is a Th1 response, the cytokine levels seem to indicate a switch towards a Th2/Th17 mixed response."

The cytokine profile indicates a stage-dependent shift toward Th2/Th17 responses during disease progression.

Bird Antigen-Driven Humoral Response

Bird antigen exposure triggers B cell activation and elevated serum IgG/IgA to avian proteins in bird-related hypersensitivity pneumonitis.

B cell CL:0000236

B cell activation GO:0042113 antigen processing and presentation GO:0019882

lung UBERON:0002048

Downstream

Dyspnea Bird-antigen sensitization is part of the immune-mediated interstitial lung disease that manifests with dyspnea.

Cough Bird-antigen sensitization is part of the immune-mediated interstitial lung disease that manifests with cough.

Show evidence (1 reference)

PMID:33041192 SUPPORT Human Clinical

"The levels of sIgG/sIgA against the bird antigens of the three species were significantly higher in subjects with acute bird-related HP and chronic bird-related HP with acute episodes (recurrent type) than in the control subjects."

Elevated bird-specific IgG/IgA in affected patients supports a humoral immune response to avian antigens.

Species-Specific Bird Antigen Panels

Diagnostic panels for bird-related hypersensitivity pneumonitis use antigens from pigeon, parrot, and budgerigar species.

Show evidence (1 reference)

PMID:33041192 SUPPORT Human Clinical

"We executed a clinical performance test by conducting a multi-institutional study to measure the levels of sIgG/sIgA against pigeon, parrot and budgerigar antigens by the ImmunoCAP® system in 29 acute and 46 chronic bird-related HP patients."

The study explicitly lists pigeon, parrot, and budgerigar antigens as the species used in standardized antibody testing for bird-related HP.

Classical Monocyte Enrichment

Fibrotic hypersensitivity pneumonitis shows elevated classical monocytes enriched for CCL3hi/CCL4hi and S100Ahi states.

monocyte CL:0000576

chemokine-mediated signaling pathway GO:0070098

lung UBERON:0002048

Downstream

Monocyte-to-SPP1hi Macrophage Differentiation Enriched classical monocyte states feed the profibrotic macrophage differentiation trajectory.

Show evidence (1 reference)

PMID:38924775 SUPPORT Human Clinical

"Compared with control samples, FHP has elevated classical monocytes (adjusted-P = 2.5 × 10-3) and is enriched in CCL3hi/CCL4hi and S100Ahi classical monocytes (adjusted-P < 2.2 × 10-16)."

Single-cell profiling identifies enriched classical monocyte states in fibrotic HP.

Monocyte-to-SPP1hi Macrophage Differentiation

Specific classical monocyte states differentiate into SPP1hi lung macrophages associated with fibrosis.

monocyte CL:0000576 macrophage CL:0000235

lung UBERON:0002048

Downstream

Pulmonary Fibrosis SPP1-high lung macrophages are associated with the fibrotic remodeling phenotype in fibrotic hypersensitivity pneumonitis.

Show evidence (1 reference)

PMID:38924775 SUPPORT Human Clinical

"Trajectory analyses demonstrate that S100Ahi classical monocytes differentiate into SPP1hi lung macrophages associated with fibrosis."

Trajectory analyses link classical monocytes to profibrotic macrophages in fibrotic HP.

Cytotoxic T Cell Program with Profibrotic Signaling

Fibrotic hypersensitivity pneumonitis features GZMhi cytotoxic T cells with transcriptional programs implicating TGFβ, TNFα, and NFκB pathways.

T cell CL:0000084

T cell activation GO:0042110

lung UBERON:0002048

Downstream

Pulmonary Fibrosis Cytotoxic T cells with TGF-beta, TNF-alpha, and NF-kappaB programs are modeled as part of the profibrotic inflammatory branch.

Show evidence (1 reference)

PMID:38924775 SUPPORT Human Clinical

"Compared with both control subjects and IPF, cells from patients with FHP are significantly enriched in GZMhi cytotoxic T cells. These cells exhibit TF activities indicative of TGFβ and TNFα and NFκB pathways."

Cytotoxic T cell enrichment with profibrotic signaling programs supports a T cell-driven inflammatory mechanism.

MMP14-High Macrophage Profibrotic Activity

MMP14-high macrophages with an M2-like phenotype promote fibroblast-to-myofibroblast transition in hypersensitivity pneumonitis models, contributing to fibrotic remodeling.

alveolar macrophage CL:0000583

extracellular matrix organization GO:0030198

alveolus of lung UBERON:0002299

Downstream

Pulmonary Fibrosis MMP14-high macrophage promotion of fibroblast-to-myofibroblast transition contributes to pulmonary fibrosis.

Show evidence (1 reference)

PMID:38218353 SUPPORT Model Organism

"we identified MMP14high macrophage subcluster with a predominant M2 phenotype that exhibited higher activity in promoting fibroblast-to myofibroblast transition (FMT)."

The study identifies a macrophage subset driving fibroblast-to-myofibroblast transition, a key fibrotic remodeling process.

TLR2 and NF-κB Regulation of MMP14 and Exosome Secretion

TLR2 and NF-κB signaling regulate MMP14 expression and macrophage exosome secretion in antigen-stimulated hypersensitivity pneumonitis models.

macrophage CL:0000235

Downstream

MMP14-High Macrophage Profibrotic Activity TLR2 and NF-kappaB signaling regulate the MMP14-high macrophage profibrotic program.

Show evidence (1 reference)

PMID:38218353 SUPPORT Model Organism

"We demonstrated that suppressing toll-like receptor 2 (TLR2) and nuclear factor kappa-B (NF-κB) could attenuate MMP14 expression and exosome secretion in macrophages stimulation with SR-Ag."

The abstract links TLR2/NF-κB signaling to MMP14 regulation and exosome secretion in HP macrophages.

✶

Histopathology

1

Alveolitis with Mononuclear Infiltration

Transbronchial lung biopsy may show alveolitis due to mononuclear cell infiltration.

Show evidence (1 reference)

PMID:14503346 SUPPORT Human Clinical

"a transbronchial lung biopsy (TBLB) specimen showed alveolitis due to the infiltration of mononuclear cells."

The case report documents biopsy-confirmed alveolitis in bird fancier's lung.

⬡

Pathograph

Use the checkboxes to hide or show graph categories. Hover nodes for evidence and cross-linked metadata.

●

Phenotypes

6

Metabolism 1

Fever OCCASIONAL Fever HP:0001945

Show evidence (1 reference)

PMID:14503346 PARTIAL Human Clinical

"A 57-year-old woman was admitted to our hospital because of cough and low-grade fever for 2 months and shortness of breath for 2 weeks."

The case report documents low-grade fever in bird fancier's lung.

Respiratory 4

Dyspnea FREQUENT Dyspnea HP:0002094

Show evidence (2 references)

PMID:14503346 PARTIAL Human Clinical

"A 57-year-old woman was admitted to our hospital because of cough and low-grade fever for 2 months and shortness of breath for 2 weeks."

The case report documents shortness of breath in bird fancier's lung.

PMID:39958101 PARTIAL Human Clinical

"We present the case of a 43-year-old male pigeon keeper with an eight-week history of progressive dyspnea on exertion and intermittent chest pain."

The case report describes progressive dyspnea on exertion in BFL.

Cough FREQUENT Cough HP:0012735

Show evidence (1 reference)

PMID:14503346 PARTIAL Human Clinical

"A 57-year-old woman was admitted to our hospital because of cough and low-grade fever for 2 months and shortness of breath for 2 weeks."

The case report describes cough in bird fancier's lung.

Pulmonary Fibrosis OCCASIONAL Pulmonary fibrosis HP:0002206

Show evidence (4 references)

PMID:37028940 SUPPORT Human Clinical

"Fibrotic hypersensitivity pneumonitis (FHP) is an irreversible lung disease with high morbidity and mortality."

The trial focuses on fibrotic hypersensitivity pneumonitis, supporting pulmonary fibrosis as a clinical phenotype.

PMID:32145830 PARTIAL Human Clinical

"the rate of decline in FVC (mL/year) over 52 weeks in patients who received at least one dose of nintedanib or placebo in five prespecified subgroups based on the ILD diagnoses documented by the investigators: hypersensitivity pneumonitis"

The INBUILD subgroup analysis includes hypersensitivity pneumonitis within progressive fibrosing ILD populations, supporting a fibrotic phenotype.

PMID:24480143 PARTIAL Human Clinical

"In the 3 diseases, most important prognosis-predicting factor is the extent of fibrotic score (the extent of honeycombing and reticulation) calculated on high-resolution computed tomography scans or fibrosis estimated on chest radiographs."

Chronic HP is discussed alongside fibrotic scoring on HRCT, reinforcing pulmonary fibrosis as a key disease feature.

+ 1 more reference

Hypoxemia OCCASIONAL Hypoxemia HP:0012418

Show evidence (1 reference)

PMID:11131880 PARTIAL Human Clinical

"A 47-year-old woman, without significant past medical history, presented an acute dyspnea with hypoxia, marked pulmonary arterial hypertension (PAH) and signs of right heart failure."

The case demonstrates hypoxia as part of acute bird hypersensitivity pneumonitis.

Constitutional 1

Fatigue OCCASIONAL Fatigue HP:0012378

Show evidence (1 reference)

PMID:6761066 SUPPORT Human Clinical

"Chronically, these diseases may present with the gradual onset of cough, dyspnea on exertion, fatigue, anorexia, and weight loss which may progress to pulmonary fibrosis or severe pulmonary insufficiency."

The clinical review describes fatigue among chronic hypersensitivity pneumonitis presentations.

🧬

Genetic Associations

2

MUC5B (Susceptibility risk in fibrotic hypersensitivity pneumonitis (non-causal))

Gene: MUC5B hgnc:7516

Show evidence (1 reference)

PMID:38309995 SUPPORT Human Clinical

"MUC5B rs35705950 and three neighboring TOLLIP variants (rs3750920, rs111521887, and rs5743894) were associated with increased susceptibility to fHP."

The case-control study reports MUC5B association with susceptibility.

TOLLIP (Susceptibility risk in fibrotic hypersensitivity pneumonitis (non-causal))

Gene: TOLLIP hgnc:16476

Show evidence (1 reference)

PMID:38309995 SUPPORT Human Clinical

"MUC5B rs35705950 and three neighboring TOLLIP variants (rs3750920, rs111521887, and rs5743894) were associated with increased susceptibility to fHP."

The study identifies TOLLIP variants associated with fibrotic HP.

💊

Medical Actions

4

Prednisone and Azathioprine

Action: corticosteroid agent therapy MAXO:0000640

Agent: prednisone CHEBI:8382 azathioprine CHEBI:2948

Glucocorticoid therapy with prednisone, sometimes combined with azathioprine, has been used in chronic hypersensitivity pneumonitis.

Show evidence (2 references)

clinicaltrials:NCT02496182 SUPPORT Human Clinical

"Actually HP has been treated with Prednisone and occasionally with Azathioprine, but unfortunately the treatment with these drugs have not an effective result to treat the interstitial fibrosis."

The trial summary notes existing use of prednisone and azathioprine in chronic hypersensitivity pneumonitis.

PMID:39958101 SUPPORT Human Clinical

"The patient was diagnosed with BFL and treated with a tapering regimen of oral corticosteroids, starting at 40 mg/day."

The case report documents corticosteroid treatment for BFL.

Mycophenolate Mofetil or Azathioprine

Action: immunosuppressive therapy Ontology label: immune suppressant agent therapy MAXO:0000297

Agent: mycophenolate mofetil CHEBI:8764 azathioprine CHEBI:2948

Immunosuppressive pharmacotherapy with mycophenolate mofetil or azathioprine has been used in chronic hypersensitivity pneumonitis and associated with improved DLCO.

Show evidence (1 reference)

PMID:27816444 PARTIAL Human Clinical

"We aimed to determine the effect of treatment with mycophenolate mofetil (MMF) or azathioprine (AZA) on lung function in patients with cHP."

The study explicitly evaluates MMF and azathioprine therapy in chronic hypersensitivity pneumonitis.

Pirfenidone

Action: targeted therapy Ontology label: Targeted Therapy NCIT:C93352

Agent: pirfenidone CHEBI:32016

Antifibrotic pharmacotherapy evaluated for fibrotic hypersensitivity pneumonitis.

Show evidence (2 references)

PMID:37028940 SUPPORT Human Clinical

"Pirfenidone was found to be safe and improved PFS in patients with FHP."

The randomized trial reports improved progression-free survival with pirfenidone in fibrotic hypersensitivity pneumonitis.

clinicaltrials:NCT02958917 SUPPORT Human Clinical

"The use of pirfenidone has not been approved for the treatment of FHP. It is considered experimental treatment in this study."

The trial registry specifies pirfenidone as the studied treatment in fibrotic hypersensitivity pneumonitis.

Nintedanib

Action: targeted therapy Ontology label: Targeted Therapy NCIT:C93352

Agent: nintedanib CHEBI:85164

Antifibrotic therapy shown to reduce the rate of FVC decline in progressive fibrosing ILD, including hypersensitivity pneumonitis subgroups.

Show evidence (1 reference)

PMID:32145830 SUPPORT Human Clinical

"The effect of nintedanib versus placebo on reducing the rate of FVC decline (mL/year) was consistent across the five subgroups by ILD diagnosis"

The INBUILD subgroup analysis supports nintedanib for progressive fibrosing ILD, including the hypersensitivity pneumonitis subgroup.

🌍

Environmental Factors

1

Bird Antigen Exposure

Exposure to bird proteins from bird breeding, feather products, or fertilizer with fowl droppings.

Show evidence (6 references)

PMID:33041192 SUPPORT Human Clinical

"Possible sources of bird antigens are bird breeding, feather products and fertilizer with fowl droppings."

The abstract explicitly lists common avian antigen exposure sources.

PMID:14503346 SUPPORT Human Clinical

"She had raised two budgerigars for the last 15 years and had been using a feather duvet for one year."

The case report documents direct bird exposure and feather product exposure associated with bird fancier's lung.

PMID:1053441 SUPPORT Human Clinical

"Among fifty-three Salt Lake City, Utah area pigeon fanciers, 21% were found to have the clinical picture of pigeon breeders' disease."

Pigeon fancier exposure is directly tied to bird fancier's lung in this prevalence study.

+ 3 more references

🔬

Biochemical Markers

1

Bird antigen-specific IgG/IgA antibodies (Positive)

Show evidence (3 references)

PMID:33041192 SUPPORT Human Clinical

"The levels of sIgG/sIgA against the bird antigens of the three species were significantly higher in subjects with acute bird-related HP and chronic bird-related HP with acute episodes (recurrent type) than in the control subjects."

Elevated bird-specific antibodies are reported in affected patients.

PMID:38762468 PARTIAL Human Clinical

"Serum IgG testing against pigeon serum was conducted twice using two methods: enzyme linked-immunosorbent assay (ELISA) and ImmunoCAP."

The study uses serial bird-specific IgG testing against pigeon serum in fibrotic avian HP.

PMID:40049235 SUPPORT Human Clinical

"The mean titers of anti-pigeon IgG antibody by ELISA were 0.659 ± 0.381 and 0.494 ± 0.187 in the bird-related fibrotic HP and control groups, respectively (p = 0.012)."

Anti-pigeon IgG titers are higher in bird-related fibrotic HP, supporting serologic evidence for avian antigen exposure.

🔀

Differential Diagnoses

3

Conditions with similar clinical presentations that must be differentiated from Bird Fancier's Lung:

Idiopathic Pulmonary Fibrosis MONDO:0800504

Overlapping Features Idiopathic pulmonary fibrosis can mimic chronic hypersensitivity pneumonitis with dyspnea and fibrosis, but has distinct HRCT distribution and feature patterns.

Distinguishing Features

Honeycombing with lower lung zone predominance on HRCT
Absence of centrilobular small nodules

Show evidence (1 reference)

PMID:24480143 SUPPORT Human Clinical

"In idiopathic pulmonary fibrosis or usual interstitial pneumonia, however, the presence of honeycombing with lower lung zone predominance and the absence of centrilobular small nodules are important findings that allow us to differentiate the disease from chronic HP or advanced-stage sarcoidosis."

HRCT findings distinguishing IPF from chronic HP are explicitly described.

Pulmonary Sarcoidosis MONDO:0019338

Overlapping Features Advanced-stage sarcoidosis can present with fibrotic lung changes but shows a characteristic upper and mid-lung predominance on HRCT.

Distinguishing Features

Upper and middle lung zone predominance with lung bases usually spared
Reticulation, traction bronchiectasis, architectural distortion, and honeycomblike cysts

Show evidence (1 reference)

PMID:24480143 SUPPORT Human Clinical

"In advanced-stage sarcoidosis, patchy areas of reticulation, traction bronchiectasis, architectural distortion, honeycomblike cysts, bullae, and paracicatricial emphysema are observed in the upper and middle lung zones. Lung bases are usually spared."

The abstract details HRCT patterns that distinguish advanced-stage sarcoidosis from chronic HP.

Hypersensitivity Pneumonitis from Home Mold Exposure MONDO:0017853

Overlapping Features Non-avian hypersensitivity pneumonitis triggered by home mold exposure can present with similar ILD features.

Distinguishing Features

Home mold exposure identified as culprit antigen
Similar ILD features without avian exposure history

Show evidence (1 reference)

PMID:40338891 SUPPORT Human Clinical

"Home mold exposure was identified as the culprit antigen in 54 of 231 hypersensitivity pneumonitis patients."

The cohort documents HP driven by home mold exposure, supporting mold-related HP as a non-avian differential diagnosis.

📊

Related Datasets

2

RNA-Sequencing of Chronic hypersensitivity pneumonitis compared with Idiopathic Pulmonary Fibrosis and Control Lung geo:GSE150910

Bulk RNA-seq of whole lung tissue from chronic hypersensitivity pneumonitis, idiopathic pulmonary fibrosis, and control samples.

human BULK RNA SEQ

lung tissue

Conditions: hypersensitivity pneumonitis idiopathic pulmonary fibrosis normal lung

PMID:32602730

GEO record includes HP, IPF, and control whole-lung RNA-seq samples.

Show evidence (1 reference)

PMID:32602730 SUPPORT Human Clinical

"Transcriptome analysis of lung samples from CHP (n = 82), IPF (n = 103), and unaffected controls (n = 103) was conducted."

The study reports bulk transcriptome profiling of lung samples from chronic HP, IPF, and controls, matching the dataset description.

Single-Cell Analysis Reveals Novel Immune Perturbations in Fibrotic Hypersensitivity Pneumonitis geo:GSE271789

Single-cell and single-nucleus RNA-seq of PBMCs and BAL cells from fibrotic hypersensitivity pneumonitis, idiopathic pulmonary fibrosis, and controls.

human SINGLE CELL RNA SEQ

peripheral blood mononuclear cell CL:2000001 bronchoalveolar lavage

Conditions: fibrotic hypersensitivity pneumonitis idiopathic pulmonary fibrosis healthy control

PMID:38924775

GEO record linked to AJRCCM 2024 single-cell study profiling PBMC and BAL.

Show evidence (1 reference)

PMID:38924775 SUPPORT Human Clinical

"Single-cell 5' RNA sequencing was conducted on peripheral blood mononuclear cells and BAL cells obtained from 45 patients with FHP, 63 patients with idiopathic pulmonary fibrosis (IPF), 4 patients with nonfibrotic hypersensitivity pneumonitis, and 36 healthy control subjects in the United States..."

The abstract documents single-cell sequencing of PBMC and BAL cells from fibrotic HP, IPF, and controls, aligning with the dataset.

🔬

Clinical Trials

3

NCT02958917 PHASE_II TERMINATED

Randomized, double-blind, placebo-controlled study evaluating pirfenidone in fibrotic hypersensitivity pneumonitis.

Target Phenotypes: Dyspnea HP:0002094 Pulmonary fibrosis HP:0002206

Show evidence (1 reference)

clinicaltrials:NCT02958917 SUPPORT Human Clinical

"Patients are being offered participation in this pirfenidone trial because They have been diagnosed with fibrotic hypersensitivity pneumonitis (FHP), a type of interstitial lung disease (ILD)."

The registry entry specifies the trial population and disease focus.

NCT02496182 PHASE_II UNKNOWN

Study evaluating addition of pirfenidone to prednisone and azathioprine in chronic hypersensitivity pneumonitis with pulmonary fibrosis.

Target Phenotypes: Pulmonary fibrosis HP:0002206 Cough HP:0012735

Show evidence (1 reference)

clinicaltrials:NCT02496182 SUPPORT Human Clinical

"the investigators propose to evaluate the addition of Pirfenidone to the actual treatment with Prednisone and Azathioprine in the treatment of patients with Pulmonary Fibrosis secondary to a Chronic Hypersensitivity Pneumonitis."

The registry summary outlines treatment strategy and target population.

NCT04844359 NOT_APPLICABLE ACTIVE_NOT_RECRUITING

Observational study developing and validating a prognostic blood transcriptomic signature in chronic hypersensitivity pneumonitis.

Target Phenotypes: Pulmonary fibrosis HP:0002206 Dyspnea HP:0002094

Show evidence (1 reference)

clinicaltrials:NCT04844359 SUPPORT Human Clinical

"Up to 150 patients with hypersensitivity pneumonitis will be enrolled at 7 clinical centers across the United States. Patients will be followed for 24 months to determine if biomarkers in the blood can predict disease progression."

The registry summary describes enrollment and biomarker-focused outcomes.

{ }

Source YAML

click to show

name: Bird Fancier's Lung
creation_date: '2026-01-30T23:42:47Z'
updated_date: '2026-05-08T16:21:17Z'
category: Respiratory Disease
parents:
- Respiratory Disease
- Inflammatory Lung Disease
has_subtypes:
- name: Recurrent chronic bird fancier's lung
  description: Chronic BFL with recurrent acute episodes that progress to interstitial pulmonary fibrosis.
  evidence:
  - reference: PMID:12839317
    reference_title: "Clinical features of recurrent and insidious chronic bird fancier's lung."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "One subgroup of patients develops interstitial pulmonary fibrosis after recurrent acute episodes (recurrent BFL)"
    explanation: The abstract defines a recurrent chronic BFL subtype marked by recurrent acute episodes and fibrotic progression.
- name: Insidious chronic bird fancier's lung
  description: Chronic BFL with slowly progressive respiratory disease without a history of acute episodes.
  evidence:
  - reference: PMID:12839317
    reference_title: "Clinical features of recurrent and insidious chronic bird fancier's lung."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the other subgroup of patients has no history of acute episodes but has slowly progressive chronic respiratory disease (insidious BFL)."
    explanation: The abstract defines an insidious subtype with slow progression and no acute episode history.
disease_term:
  preferred_term: bird fancier's lung
  term:
    id: MONDO:0005668
    label: bird fancier's lung
description: Immune-mediated interstitial lung disease caused by repeated inhalation of avian proteins, leading to inflammatory and sometimes fibrotic lung injury.
synonyms:
- Bird-related hypersensitivity pneumonitis
- Bird-related HP
- BRHP
- Avian hypersensitivity pneumonitis
- Avian HP
- Bird fancier's lung
- Pigeon breeder's disease
- Pigeon breeders' disease
- Pigeon fancier's lung
prevalence:
- population: United Kingdom
  measure_type: ANNUAL_INCIDENCE
  prevalence_class: BAND_1_9_PER_100000
  rate_per_100000: 1.0
  percentage: 0.001
  notes: Reported overall annual incidence of hypersensitivity pneumonitis in a British study (approximately 1 per 100,000 per year).
  evidence:
  - reference: PMID:23101639
    reference_title: "[Domestic hypersensitivity pneumonitis]."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Domestic hypersensitivity pneumonitis (HP) cases are relatively widespread, with an overall annual incidence of approximately 1/100,000 reported in a British study covering several million patients."
    explanation: The review reports a UK annual incidence estimate that can be used as a population-level rate for HP including bird fancier's lung.
epidemiology:
- name: High prevalence among pigeon fanciers
  description: Pigeon fanciers have a high prevalence of bird fancier's lung in regional cohort studies.
  evidence:
  - reference: PMID:1053441
    reference_title: "Pigeon breeders' disease--a prevalence study and review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among fifty-three Salt Lake City, Utah area pigeon fanciers, 21% were found to have the clinical picture of pigeon breeders' disease."
    explanation: The study documents a high prevalence among exposed pigeon fanciers.
- name: Common form of hypersensitivity pneumonitis
  description: Bird fancier's lung is a common form of hypersensitivity pneumonitis among exposed populations.
  evidence:
  - reference: PMID:21870048
    reference_title: "Bird fancier's lung: a state-of-the-art review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Bird fancier's lung (BFL) resulting from avian antigen exposure is a very common form of hypersensitivity pneumonitis."
    explanation: The review describes BFL as a very common form of HP.
progression:
- phase: Acute
  notes: Acute hypersensitivity pneumonitis presents within hours after heavy antigen exposure.
  evidence:
  - reference: PMID:6761066
    reference_title: "Immunology of hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Symptoms usually begin 4 to 6 hr after exposure to large quantities of causative organic dust."
    explanation: The review describes rapid onset after exposure in acute disease.
- phase: Chronic
  notes: Chronic disease shows gradual symptom onset and can progress to pulmonary fibrosis.
  evidence:
  - reference: PMID:6761066
    reference_title: "Immunology of hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Chronically, these diseases may present with the gradual onset of cough, dyspnea on exertion, fatigue, anorexia, and weight loss which may progress to pulmonary fibrosis or severe pulmonary insufficiency."
    explanation: The review notes gradual onset and progression to fibrosis.
stages:
- name: Acute/Inflammatory
  description: Acute hypersensitivity pneumonitis with rapid symptom onset after high-level antigen exposure.
  evidence:
  - reference: PMID:6761066
    reference_title: "Immunology of hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Symptoms usually begin 4 to 6 hr after exposure to large quantities of causative organic dust."
    explanation: Rapid symptom onset is characteristic of acute disease.
- name: Chronic/Fibrotic
  description: Chronic hypersensitivity pneumonitis with gradual onset and risk of pulmonary fibrosis.
  evidence:
  - reference: PMID:6761066
    reference_title: "Immunology of hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Chronically, these diseases may present with the gradual onset of cough, dyspnea on exertion, fatigue, anorexia, and weight loss which may progress to pulmonary fibrosis or severe pulmonary insufficiency."
    explanation: The review describes chronic progression with fibrotic outcomes.
pathophysiology:
- name: Exposure to Avian Proteins
  description: Repeated inhalation of avian proteins from bird droppings, feathers, or serum triggers bird-related hypersensitivity pneumonitis.
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: DOI:10.3390/ijms24032884
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Bird-related hypersensitivity pneumonitis (BRHP) is an interstitial lung disease induced by avian proteins."
    explanation: The review defines BRHP as an avian protein-induced interstitial lung disease.
  - reference: PMID:39958101
    reference_title: "Advanced Imaging and Occupational History in the Diagnosis of Bird Fancier's Lung: A Case Report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Bird fancier's lung (BFL) is a subtype of hypersensitivity pneumonitis (HP), an immune-mediated interstitial lung disease (ILD) resulting from the repeated inhalation of avian proteins found in bird droppings, feathers, and serum."
    explanation: The case report links BFL to repeated inhalation of avian proteins as the causative trigger for interstitial lung disease.
  - reference: PMID:33318919
    reference_title: "Bird Fancier's lung: An underdiagnosed etiology of dyspnea."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Bird Fancier's Lung is a type of hypersensitivity pneumonitis, an immunologically mediated lung disease due to repetitive exposure of air-borne avian antigen."
    explanation: The report characterizes BFL as an immune-mediated interstitial lung disease driven by repetitive avian antigen exposure.
  downstream:
  - target: Bird Antigen-Driven Humoral Response
    description: >-
      Repeated avian antigen exposure triggers measurable bird-specific
      antibody responses.
    causal_link_type: INDIRECT_KNOWN_INTERMEDIATES
  - target: Th1/Th2 to Th2/Th17 Cytokine Shift
    description: >-
      Antigen exposure initiates the hypersensitivity-pneumonitis immune
      response that shifts across disease stages.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Dyspnea
    description: >-
      Immune-mediated interstitial lung disease from repeated avian antigen
      exposure clinically manifests with dyspnea.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Cough
    description: >-
      Immune-mediated interstitial lung disease from repeated avian antigen
      exposure clinically manifests with cough.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Expansion of Resident Monocytes and Interstitial Macrophages
  description: Bird antigen exposure is associated with increased resident monocytes, interstitial macrophages, and type 2 dendritic cells in the lung.
  cell_types:
  - preferred_term: monocyte
    term:
      id: CL:0000576
      label: monocyte
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: dendritic cell
    term:
      id: CL:0000451
      label: dendritic cell
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: DOI:10.3390/ijms24032884
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Both groups presented increases in resident monocytes, interstitial macrophages and type 2 dendritic cells (DCs), but also reductions in inflammatory monocytes, alveolar macrophages and tolerogenic DCs compared with their control groups."
    explanation: The mouse model reports increased resident monocytes, interstitial macrophages, and type 2 dendritic cells after bird antigen exposure.
  downstream:
  - target: Th1/Th2 to Th2/Th17 Cytokine Shift
    description: >-
      Monocyte, macrophage, and dendritic-cell remodeling is modeled upstream
      of the stage-dependent T-cell cytokine shift.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Reduction of Inflammatory Monocytes and Alveolar Macrophages
  description: Bird antigen exposure is associated with reduced inflammatory monocytes, alveolar macrophages, and tolerogenic dendritic cells in the lung.
  cell_types:
  - preferred_term: monocyte
    term:
      id: CL:0000576
      label: monocyte
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  - preferred_term: dendritic cell
    term:
      id: CL:0000451
      label: dendritic cell
  - preferred_term: alveolar macrophage
    term:
      id: CL:0000583
      label: alveolar macrophage
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: DOI:10.3390/ijms24032884
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "Both groups presented increases in resident monocytes, interstitial macrophages and type 2 dendritic cells (DCs), but also reductions in inflammatory monocytes, alveolar macrophages and tolerogenic DCs compared with their control groups."
    explanation: The same experiment reports reduced inflammatory monocytes, alveolar macrophages, and tolerogenic dendritic cells.
- name: Th1/Th2 to Th2/Th17 Cytokine Shift
  description: Early disease shows a mixed Th1/Th2 response, while progression shifts toward a Th2/Th17 mixed response.
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  biological_processes:
  - preferred_term: T cell activation
    term:
      id: GO:0042110
      label: T cell activation
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: DOI:10.3390/ijms24032884
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "In the first stages of BRHP, there is a mixed Th1/Th2 immune response, while during the progression of the disease, although there is a Th1 response, the cytokine levels seem to indicate a switch towards a Th2/Th17 mixed response."
    explanation: The cytokine profile indicates a stage-dependent shift toward Th2/Th17 responses during disease progression.
  downstream:
  - target: Fever
    description: Acute inflammatory hypersensitivity pneumonitis can produce flu-like systemic symptoms.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Fatigue
    description: Chronic inflammatory hypersensitivity pneumonitis can produce fatigue.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Dyspnea
    description: Lung inflammation and evolving interstitial injury produce exertional dyspnea.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Cough
    description: Lung inflammation from hypersensitivity pneumonitis produces cough.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Hypoxemia
    description: Active inflammatory interstitial lung disease can impair gas exchange.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Bird Antigen-Driven Humoral Response
  description: Bird antigen exposure triggers B cell activation and elevated serum IgG/IgA to avian proteins in bird-related hypersensitivity pneumonitis.
  cell_types:
  - preferred_term: B cell
    term:
      id: CL:0000236
      label: B cell
  biological_processes:
  - preferred_term: B cell activation
    term:
      id: GO:0042113
      label: B cell activation
  - preferred_term: antigen processing and presentation
    term:
      id: GO:0019882
      label: antigen processing and presentation
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: PMID:33041192
    reference_title: "Screening and diagnosis of acute and chronic bird-related hypersensitivity pneumonitis by serum IgG and IgA antibodies to bird antigens with ImmunoCAP®."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The levels of sIgG/sIgA against the bird antigens of the three species were significantly higher in subjects with acute bird-related HP and chronic bird-related HP with acute episodes (recurrent type) than in the control subjects."
    explanation: Elevated bird-specific IgG/IgA in affected patients supports a humoral immune response to avian antigens.
  downstream:
  - target: Dyspnea
    description: >-
      Bird-antigen sensitization is part of the immune-mediated interstitial
      lung disease that manifests with dyspnea.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
  - target: Cough
    description: >-
      Bird-antigen sensitization is part of the immune-mediated interstitial
      lung disease that manifests with cough.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: Species-Specific Bird Antigen Panels
  description: Diagnostic panels for bird-related hypersensitivity pneumonitis use antigens from pigeon, parrot, and budgerigar species.
  triggers:
  - preferred_term: pigeon
    term:
      id: NCBITaxon:8932
      label: Columba livia
  - preferred_term: parrot
    term:
      id: NCBITaxon:9223
      label: Psittaciformes
  - preferred_term: budgerigar
    term:
      id: NCBITaxon:13146
      label: Melopsittacus undulatus
  evidence:
  - reference: PMID:33041192
    reference_title: "Screening and diagnosis of acute and chronic bird-related hypersensitivity pneumonitis by serum IgG and IgA antibodies to bird antigens with ImmunoCAP®."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "We executed a clinical performance test by conducting a multi-institutional study to measure the levels of sIgG/sIgA against pigeon, parrot and budgerigar antigens by the ImmunoCAP® system in 29 acute and 46 chronic bird-related HP patients."
    explanation: The study explicitly lists pigeon, parrot, and budgerigar antigens as the species used in standardized antibody testing for bird-related HP.
- name: Classical Monocyte Enrichment
  description: Fibrotic hypersensitivity pneumonitis shows elevated classical monocytes enriched for CCL3hi/CCL4hi and S100Ahi states.
  cell_types:
  - preferred_term: monocyte
    term:
      id: CL:0000576
      label: monocyte
  biological_processes:
  - preferred_term: chemokine-mediated signaling pathway
    term:
      id: GO:0070098
      label: chemokine-mediated signaling pathway
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: PMID:38924775
    reference_title: "Single-Cell Analysis Reveals Novel Immune Perturbations in Fibrotic Hypersensitivity Pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Compared with control samples, FHP has elevated classical monocytes (adjusted-P = 2.5 × 10-3) and is enriched in CCL3hi/CCL4hi and S100Ahi classical monocytes (adjusted-P < 2.2 × 10-16)."
    explanation: Single-cell profiling identifies enriched classical monocyte states in fibrotic HP.
  downstream:
  - target: Monocyte-to-SPP1hi Macrophage Differentiation
    description: >-
      Enriched classical monocyte states feed the profibrotic macrophage
      differentiation trajectory.
    causal_link_type: DIRECT
- name: Monocyte-to-SPP1hi Macrophage Differentiation
  description: Specific classical monocyte states differentiate into SPP1hi lung macrophages associated with fibrosis.
  cell_types:
  - preferred_term: monocyte
    term:
      id: CL:0000576
      label: monocyte
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: PMID:38924775
    reference_title: "Single-Cell Analysis Reveals Novel Immune Perturbations in Fibrotic Hypersensitivity Pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Trajectory analyses demonstrate that S100Ahi classical monocytes differentiate into SPP1hi lung macrophages associated with fibrosis."
    explanation: Trajectory analyses link classical monocytes to profibrotic macrophages in fibrotic HP.
  downstream:
  - target: Pulmonary Fibrosis
    description: >-
      SPP1-high lung macrophages are associated with the fibrotic remodeling
      phenotype in fibrotic hypersensitivity pneumonitis.
    causal_link_type: DIRECT
- name: Cytotoxic T Cell Program with Profibrotic Signaling
  description: Fibrotic hypersensitivity pneumonitis features GZMhi cytotoxic T cells with transcriptional programs implicating TGFβ, TNFα, and NFκB pathways.
  cell_types:
  - preferred_term: T cell
    term:
      id: CL:0000084
      label: T cell
  biological_processes:
  - preferred_term: T cell activation
    term:
      id: GO:0042110
      label: T cell activation
  locations:
  - preferred_term: lung
    term:
      id: UBERON:0002048
      label: lung
  evidence:
  - reference: PMID:38924775
    reference_title: "Single-Cell Analysis Reveals Novel Immune Perturbations in Fibrotic Hypersensitivity Pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Compared with both control subjects and IPF, cells from patients with FHP are significantly enriched in GZMhi cytotoxic T cells. These cells exhibit TF activities indicative of TGFβ and TNFα and NFκB pathways."
    explanation: Cytotoxic T cell enrichment with profibrotic signaling programs supports a T cell-driven inflammatory mechanism.
  downstream:
  - target: Pulmonary Fibrosis
    description: >-
      Cytotoxic T cells with TGF-beta, TNF-alpha, and NF-kappaB programs are
      modeled as part of the profibrotic inflammatory branch.
    causal_link_type: INDIRECT_UNKNOWN_INTERMEDIATES
- name: MMP14-High Macrophage Profibrotic Activity
  description: MMP14-high macrophages with an M2-like phenotype promote fibroblast-to-myofibroblast transition in hypersensitivity pneumonitis models, contributing to fibrotic remodeling.
  cell_types:
  - preferred_term: alveolar macrophage
    term:
      id: CL:0000583
      label: alveolar macrophage
  biological_processes:
  - preferred_term: extracellular matrix organization
    term:
      id: GO:0030198
      label: extracellular matrix organization
  locations:
  - preferred_term: alveolus of lung
    term:
      id: UBERON:0002299
      label: alveolus of lung
  evidence:
  - reference: PMID:38218353
    reference_title: "MMP14(high) macrophages orchestrate progressive pulmonary fibrosis in SR-Ag-induced hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "we identified MMP14high macrophage subcluster with a predominant M2 phenotype that exhibited higher activity in promoting fibroblast-to myofibroblast transition (FMT)."
    explanation: The study identifies a macrophage subset driving fibroblast-to-myofibroblast transition, a key fibrotic remodeling process.
  downstream:
  - target: Pulmonary Fibrosis
    description: >-
      MMP14-high macrophage promotion of fibroblast-to-myofibroblast transition
      contributes to pulmonary fibrosis.
    causal_link_type: DIRECT
- name: TLR2 and NF-κB Regulation of MMP14 and Exosome Secretion
  description: TLR2 and NF-κB signaling regulate MMP14 expression and macrophage exosome secretion in antigen-stimulated hypersensitivity pneumonitis models.
  cell_types:
  - preferred_term: macrophage
    term:
      id: CL:0000235
      label: macrophage
  evidence:
  - reference: PMID:38218353
    reference_title: "MMP14(high) macrophages orchestrate progressive pulmonary fibrosis in SR-Ag-induced hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "We demonstrated that suppressing toll-like receptor 2 (TLR2) and nuclear factor kappa-B (NF-κB) could attenuate MMP14 expression and exosome secretion in macrophages stimulation with SR-Ag."
    explanation: The abstract links TLR2/NF-κB signaling to MMP14 regulation and exosome secretion in HP macrophages.
  downstream:
  - target: MMP14-High Macrophage Profibrotic Activity
    description: >-
      TLR2 and NF-kappaB signaling regulate the MMP14-high macrophage
      profibrotic program.
    causal_link_type: DIRECT
phenotypes:
- category: Respiratory
  name: Dyspnea
  frequency: FREQUENT
  description: Exertional or progressive shortness of breath associated with inflammatory and fibrotic lung involvement.
  phenotype_term:
    preferred_term: Dyspnea
    term:
      id: HP:0002094
      label: Dyspnea
  evidence:
  - reference: PMID:14503346
    reference_title: "[A case of acute bird fancier's lung caused by feather duvet]."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "A 57-year-old woman was admitted to our hospital because of cough and low-grade fever for 2 months and shortness of breath for 2 weeks."
    explanation: The case report documents shortness of breath in bird fancier's lung.
  - reference: PMID:39958101
    reference_title: "Advanced Imaging and Occupational History in the Diagnosis of Bird Fancier's Lung: A Case Report."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "We present the case of a 43-year-old male pigeon keeper with an eight-week history of progressive dyspnea on exertion and intermittent chest pain."
    explanation: The case report describes progressive dyspnea on exertion in BFL.
- category: Respiratory
  name: Cough
  frequency: FREQUENT
  description: Persistent or recurrent cough associated with hypersensitivity pneumonitis.
  phenotype_term:
    preferred_term: Cough
    term:
      id: HP:0012735
      label: Cough
  evidence:
  - reference: PMID:14503346
    reference_title: "[A case of acute bird fancier's lung caused by feather duvet]."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "A 57-year-old woman was admitted to our hospital because of cough and low-grade fever for 2 months and shortness of breath for 2 weeks."
    explanation: The case report describes cough in bird fancier's lung.
- category: Respiratory
  name: Pulmonary Fibrosis
  frequency: OCCASIONAL
  description: Fibrotic remodeling in chronic or progressive disease.
  phenotype_term:
    preferred_term: Pulmonary fibrosis
    term:
      id: HP:0002206
      label: Pulmonary fibrosis
  evidence:
  - reference: PMID:37028940
    reference_title: "Pirfenidone in fibrotic hypersensitivity pneumonitis: a double-blind, randomised clinical trial of efficacy and safety."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Fibrotic hypersensitivity pneumonitis (FHP) is an irreversible lung disease with high morbidity and mortality."
    explanation: The trial focuses on fibrotic hypersensitivity pneumonitis, supporting pulmonary fibrosis as a clinical phenotype.
  - reference: PMID:32145830
    reference_title: "Nintedanib in patients with progressive fibrosing interstitial lung diseases-subgroup analyses by interstitial lung disease diagnosis in the INBUILD trial: a randomised, double-blind, placebo-controlled, parallel-group trial."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "the rate of decline in FVC (mL/year) over 52 weeks in patients who received at least one dose of nintedanib or placebo in five prespecified subgroups based on the ILD diagnoses documented by the investigators: hypersensitivity pneumonitis"
    explanation: The INBUILD subgroup analysis includes hypersensitivity pneumonitis within progressive fibrosing ILD populations, supporting a fibrotic phenotype.
  - reference: PMID:24480143
    reference_title: "Chronic hypersensitivity pneumonitis and pulmonary sarcoidosis: differentiation from usual interstitial pneumonia using high-resolution computed tomography."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "In the 3 diseases, most important prognosis-predicting factor is the extent of fibrotic score (the extent of honeycombing and reticulation) calculated on high-resolution computed tomography scans or fibrosis estimated on chest radiographs."
    explanation: Chronic HP is discussed alongside fibrotic scoring on HRCT, reinforcing pulmonary fibrosis as a key disease feature.
  - reference: PMID:38218353
    reference_title: "MMP14(high) macrophages orchestrate progressive pulmonary fibrosis in SR-Ag-induced hypersensitivity pneumonitis."
    supports: PARTIAL
    evidence_source: MODEL_ORGANISM
    snippet: "Importantly, it was observed that the transfer of MMP14-overexpressing macrophages into mice promoted lung inflammation and fibrosis induced by SR-Ag."
    explanation: In a hypersensitivity pneumonitis model, fibrosis is a documented outcome, supporting pulmonary fibrosis as a disease phenotype.
- category: Respiratory
  name: Hypoxemia
  frequency: OCCASIONAL
  description: Reduced blood oxygenation during active disease.
  phenotype_term:
    preferred_term: Hypoxemia
    term:
      id: HP:0012418
      label: Hypoxemia
  evidence:
  - reference: PMID:11131880
    reference_title: "[A misleading form of hypersensitivity pneumonitis]."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "A 47-year-old woman, without significant past medical history, presented an acute dyspnea with hypoxia, marked pulmonary arterial hypertension (PAH) and signs of right heart failure."
    explanation: The case demonstrates hypoxia as part of acute bird hypersensitivity pneumonitis.
- category: Constitutional
  name: Fatigue
  frequency: OCCASIONAL
  description: Systemic fatigue during symptomatic episodes.
  phenotype_term:
    preferred_term: Fatigue
    term:
      id: HP:0012378
      label: Fatigue
  evidence:
  - reference: PMID:6761066
    reference_title: "Immunology of hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Chronically, these diseases may present with the gradual onset of cough, dyspnea on exertion, fatigue, anorexia, and weight loss which may progress to pulmonary fibrosis or severe pulmonary insufficiency."
    explanation: The clinical review describes fatigue among chronic hypersensitivity pneumonitis presentations.
- category: Constitutional
  name: Fever
  frequency: OCCASIONAL
  description: Flu-like systemic symptoms during acute exposure episodes.
  phenotype_term:
    preferred_term: Fever
    term:
      id: HP:0001945
      label: Fever
  evidence:
  - reference: PMID:14503346
    reference_title: "[A case of acute bird fancier's lung caused by feather duvet]."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "A 57-year-old woman was admitted to our hospital because of cough and low-grade fever for 2 months and shortness of breath for 2 weeks."
    explanation: The case report documents low-grade fever in bird fancier's lung.
histopathology:
- name: Alveolitis with Mononuclear Infiltration
  description: Transbronchial lung biopsy may show alveolitis due to mononuclear cell infiltration.
  evidence:
  - reference: PMID:14503346
    reference_title: "[A case of acute bird fancier's lung caused by feather duvet]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "a transbronchial lung biopsy (TBLB) specimen showed alveolitis due to the infiltration of mononuclear cells."
    explanation: The case report documents biopsy-confirmed alveolitis in bird fancier's lung.
biochemical:
- name: Bird antigen-specific IgG/IgA antibodies
  notes: Elevated serum IgG/IgA antibodies to bird antigens in bird-related hypersensitivity pneumonitis.
  presence: Positive
  evidence:
  - reference: PMID:33041192
    reference_title: "Screening and diagnosis of acute and chronic bird-related hypersensitivity pneumonitis by serum IgG and IgA antibodies to bird antigens with ImmunoCAP®."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The levels of sIgG/sIgA against the bird antigens of the three species were significantly higher in subjects with acute bird-related HP and chronic bird-related HP with acute episodes (recurrent type) than in the control subjects."
    explanation: Elevated bird-specific antibodies are reported in affected patients.
  - reference: PMID:38762468
    reference_title: "Longitudinal changes in serum immunoglobulin G testing in patients with fibrotic avian hypersensitivity pneumonitis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Serum IgG testing against pigeon serum was conducted twice using two methods: enzyme linked-immunosorbent assay (ELISA) and ImmunoCAP."
    explanation: The study uses serial bird-specific IgG testing against pigeon serum in fibrotic avian HP.
  - reference: PMID:40049235
    reference_title: "Anti-chicken and anti-pigeon immunoglobulin G testing in patients with bird-related fibrotic hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The mean titers of anti-pigeon IgG antibody by ELISA were 0.659 ± 0.381 and 0.494 ± 0.187 in the bird-related fibrotic HP and control groups, respectively (p = 0.012)."
    explanation: Anti-pigeon IgG titers are higher in bird-related fibrotic HP, supporting serologic evidence for avian antigen exposure.
genetic:
- name: MUC5B
  association: Susceptibility risk in fibrotic hypersensitivity pneumonitis (non-causal)
  gene_term:
    preferred_term: MUC5B
    term:
      id: hgnc:7516
      label: MUC5B
  evidence:
  - reference: PMID:38309995
    reference_title: "Polymorphisms and haplotypes of TOLLIP and MUC5B are associated with susceptibility and survival in patients with fibrotic hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "MUC5B rs35705950 and three neighboring TOLLIP variants (rs3750920, rs111521887, and rs5743894) were associated with increased susceptibility to fHP."
    explanation: The case-control study reports MUC5B association with susceptibility.
- name: TOLLIP
  association: Susceptibility risk in fibrotic hypersensitivity pneumonitis (non-causal)
  gene_term:
    preferred_term: TOLLIP
    term:
      id: hgnc:16476
      label: TOLLIP
  evidence:
  - reference: PMID:38309995
    reference_title: "Polymorphisms and haplotypes of TOLLIP and MUC5B are associated with susceptibility and survival in patients with fibrotic hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "MUC5B rs35705950 and three neighboring TOLLIP variants (rs3750920, rs111521887, and rs5743894) were associated with increased susceptibility to fHP."
    explanation: The study identifies TOLLIP variants associated with fibrotic HP.
diagnosis:
- name: Bronchoalveolar lavage lymphocytosis
  description: BAL shows a marked increase in lymphocytes in bird fancier's lung.
  evidence:
  - reference: PMID:14503346
    reference_title: "[A case of acute bird fancier's lung caused by feather duvet]."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Bronchoalveolar lavage (BAL) revealed a marked increase in lymphocytes"
    explanation: The case report documents BAL lymphocytosis as a diagnostic finding.
- name: High-resolution computed tomography pattern
  description: HRCT shows centrilobular small nodules and lobular areas of decreased attenuation in chronic hypersensitivity pneumonitis.
  evidence:
  - reference: PMID:24480143
    reference_title: "Chronic hypersensitivity pneumonitis and pulmonary sarcoidosis: differentiation from usual interstitial pneumonia using high-resolution computed tomography."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In chronic HP, the presence of lobular areas of decreased attenuation and centrilobular small nodules and the absence of lower lung zone predominance are characteristically observed."
    explanation: The HRCT pattern distinguishes chronic HP from other fibrotic ILDs.
  - reference: PMID:39958101
    reference_title: "Advanced Imaging and Occupational History in the Diagnosis of Bird Fancier's Lung: A Case Report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "HRCT revealed bilateral diffuse centrilobular nodules, patchy ground-glass opacities, and a mosaic attenuation pattern without fibrosis, consistent with acute HP."
    explanation: The case report highlights characteristic HRCT findings in BFL.
- name: Bird antigen-specific IgG/IgA serology
  description: Elevated bird-specific IgG/IgA supports exposure attribution.
  evidence:
  - reference: PMID:33041192
    reference_title: "Screening and diagnosis of acute and chronic bird-related hypersensitivity pneumonitis by serum IgG and IgA antibodies to bird antigens with ImmunoCAP®."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The levels of sIgG/sIgA against the bird antigens of the three species were significantly higher in subjects with acute bird-related HP and chronic bird-related HP with acute episodes (recurrent type) than in the control subjects."
    explanation: Elevated bird-specific IgG/IgA is a diagnostic serologic marker.
  - reference: PMID:38762468
    reference_title: "Longitudinal changes in serum immunoglobulin G testing in patients with fibrotic avian hypersensitivity pneumonitis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "Serum IgG testing against pigeon serum was conducted twice using two methods: enzyme linked-immunosorbent assay (ELISA) and ImmunoCAP."
    explanation: Serial IgG testing against pigeon serum supports diagnostic attribution to avian antigens.
  - reference: PMID:40049235
    reference_title: "Anti-chicken and anti-pigeon immunoglobulin G testing in patients with bird-related fibrotic hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The mean titers of anti-pigeon IgG antibody by ELISA were 0.659 ± 0.381 and 0.494 ± 0.187 in the bird-related fibrotic HP and control groups, respectively (p = 0.012)."
    explanation: Elevated anti-pigeon IgG by ELISA supports diagnostic testing for bird-related fibrotic HP.
- name: Inhalation challenge test
  description: Inhalation challenge testing is a sensitive diagnostic tool for bird-related fibrotic hypersensitivity pneumonitis.
  evidence:
  - reference: PMID:35779842
    reference_title: "Validation of inhalation challenge test and serum immunoglobulin G test for bird-related fibrotic hypersensitivity pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The inhalation challenge test for bird-related fibrotic HP was more sensitive than the anti-bird IgG antibodies."
    explanation: The study reports higher sensitivity for inhalation challenge testing compared to serology.
- name: Occupational and exposure history
  description: Detailed occupational or avian exposure history is critical for diagnosing bird fancier's lung.
  evidence:
  - reference: PMID:39958101
    reference_title: "Advanced Imaging and Occupational History in the Diagnosis of Bird Fancier's Lung: A Case Report."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "A thorough occupational history uncovered significant avian antigen exposure, and a family history suggested genetic susceptibility."
    explanation: The case report emphasizes occupational history to identify avian antigen exposure.
treatments:
- name: Prednisone and Azathioprine
  description: Glucocorticoid therapy with prednisone, sometimes combined with azathioprine, has been used in chronic hypersensitivity pneumonitis.
  treatment_term:
    preferred_term: corticosteroid agent therapy
    term:
      id: MAXO:0000640
      label: corticosteroid agent therapy
    therapeutic_agent:
    - preferred_term: prednisone
      term:
        id: CHEBI:8382
        label: prednisone
    - preferred_term: azathioprine
      term:
        id: CHEBI:2948
        label: azathioprine
  evidence:
  - reference: clinicaltrials:NCT02496182
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Actually HP has been treated with Prednisone and occasionally with Azathioprine, but unfortunately the treatment with these drugs have not an effective result to treat the interstitial fibrosis."
    explanation: The trial summary notes existing use of prednisone and azathioprine in chronic hypersensitivity pneumonitis.
  - reference: PMID:39958101
    reference_title: "Advanced Imaging and Occupational History in the Diagnosis of Bird Fancier's Lung: A Case Report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The patient was diagnosed with BFL and treated with a tapering regimen of oral corticosteroids, starting at 40 mg/day."
    explanation: The case report documents corticosteroid treatment for BFL.
- name: Mycophenolate Mofetil or Azathioprine
  description: Immunosuppressive pharmacotherapy with mycophenolate mofetil or azathioprine has been used in chronic hypersensitivity pneumonitis and associated with improved DLCO.
  treatment_term:
    preferred_term: immunosuppressive therapy
    term:
      id: MAXO:0000297
      label: immune suppressant agent therapy
    therapeutic_agent:
    - preferred_term: mycophenolate mofetil
      term:
        id: CHEBI:8764
        label: mycophenolate mofetil
    - preferred_term: azathioprine
      term:
        id: CHEBI:2948
        label: azathioprine
  evidence:
  - reference: PMID:27816444
    reference_title: "Use of Mycophenolate Mofetil or Azathioprine for the Management of Chronic Hypersensitivity Pneumonitis."
    supports: PARTIAL
    evidence_source: HUMAN_CLINICAL
    snippet: "We aimed to determine the effect of treatment with mycophenolate mofetil (MMF) or azathioprine (AZA) on lung function in patients with cHP."
    explanation: The study explicitly evaluates MMF and azathioprine therapy in chronic hypersensitivity pneumonitis.
- name: Pirfenidone
  description: Antifibrotic pharmacotherapy evaluated for fibrotic hypersensitivity pneumonitis.
  treatment_term:
    preferred_term: targeted therapy
    term:
      id: NCIT:C93352
      label: Targeted Therapy
    therapeutic_agent:
    - preferred_term: pirfenidone
      term:
        id: CHEBI:32016
        label: pirfenidone
  evidence:
  - reference: PMID:37028940
    reference_title: "Pirfenidone in fibrotic hypersensitivity pneumonitis: a double-blind, randomised clinical trial of efficacy and safety."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Pirfenidone was found to be safe and improved PFS in patients with FHP."
    explanation: The randomized trial reports improved progression-free survival with pirfenidone in fibrotic hypersensitivity pneumonitis.
  - reference: clinicaltrials:NCT02958917
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The use of pirfenidone has not been approved for the treatment of FHP. It is considered experimental treatment in this study."
    explanation: The trial registry specifies pirfenidone as the studied treatment in fibrotic hypersensitivity pneumonitis.
- name: Nintedanib
  description: Antifibrotic therapy shown to reduce the rate of FVC decline in progressive fibrosing ILD, including hypersensitivity pneumonitis subgroups.
  treatment_term:
    preferred_term: targeted therapy
    term:
      id: NCIT:C93352
      label: Targeted Therapy
    therapeutic_agent:
    - preferred_term: nintedanib
      term:
        id: CHEBI:85164
        label: nintedanib
  evidence:
  - reference: PMID:32145830
    reference_title: "Nintedanib in patients with progressive fibrosing interstitial lung diseases-subgroup analyses by interstitial lung disease diagnosis in the INBUILD trial: a randomised, double-blind, placebo-controlled, parallel-group trial."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "The effect of nintedanib versus placebo on reducing the rate of FVC decline (mL/year) was consistent across the five subgroups by ILD diagnosis"
    explanation: The INBUILD subgroup analysis supports nintedanib for progressive fibrosing ILD, including the hypersensitivity pneumonitis subgroup.
differential_diagnoses:
- name: Idiopathic Pulmonary Fibrosis
  disease_term:
    preferred_term: idiopathic pulmonary fibrosis
    term:
      id: MONDO:0800504
      label: idiopathic pulmonary fibrosis
  description: Idiopathic pulmonary fibrosis can mimic chronic hypersensitivity pneumonitis with dyspnea and fibrosis, but has distinct HRCT distribution and feature patterns.
  distinguishing_features:
  - Honeycombing with lower lung zone predominance on HRCT
  - Absence of centrilobular small nodules
  evidence:
  - reference: PMID:24480143
    reference_title: "Chronic hypersensitivity pneumonitis and pulmonary sarcoidosis: differentiation from usual interstitial pneumonia using high-resolution computed tomography."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In idiopathic pulmonary fibrosis or usual interstitial pneumonia, however, the presence of honeycombing with lower lung zone predominance and the absence of centrilobular small nodules are important findings that allow us to differentiate the disease from chronic HP or advanced-stage sarcoidosis."
    explanation: HRCT findings distinguishing IPF from chronic HP are explicitly described.
- name: Pulmonary Sarcoidosis
  disease_term:
    preferred_term: sarcoidosis
    term:
      id: MONDO:0019338
      label: sarcoidosis
  description: Advanced-stage sarcoidosis can present with fibrotic lung changes but shows a characteristic upper and mid-lung predominance on HRCT.
  distinguishing_features:
  - Upper and middle lung zone predominance with lung bases usually spared
  - Reticulation, traction bronchiectasis, architectural distortion, and honeycomblike cysts
  evidence:
  - reference: PMID:24480143
    reference_title: "Chronic hypersensitivity pneumonitis and pulmonary sarcoidosis: differentiation from usual interstitial pneumonia using high-resolution computed tomography."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "In advanced-stage sarcoidosis, patchy areas of reticulation, traction bronchiectasis, architectural distortion, honeycomblike cysts, bullae, and paracicatricial emphysema are observed in the upper and middle lung zones. Lung bases are usually spared."
    explanation: The abstract details HRCT patterns that distinguish advanced-stage sarcoidosis from chronic HP.
- name: Hypersensitivity Pneumonitis from Home Mold Exposure
  disease_term:
    preferred_term: hypersensitivity pneumonitis
    term:
      id: MONDO:0017853
      label: hypersensitivity pneumonitis
  description: Non-avian hypersensitivity pneumonitis triggered by home mold exposure can present with similar ILD features.
  distinguishing_features:
  - Home mold exposure identified as culprit antigen
  - Similar ILD features without avian exposure history
  evidence:
  - reference: PMID:40338891
    reference_title: "Hypersensitivity pneumonitis associated with home mold exposure: A retrospective cohort analysis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Home mold exposure was identified as the culprit antigen in 54 of 231 hypersensitivity pneumonitis patients."
    explanation: The cohort documents HP driven by home mold exposure, supporting mold-related HP as a non-avian differential diagnosis.
environmental:
- name: Bird Antigen Exposure
  description: Exposure to bird proteins from bird breeding, feather products, or fertilizer with fowl droppings.
  exposure_term:
    preferred_term: exposure to animal waste material
    term:
      id: ECTO:7000098
      label: exposure to animal waste material
  evidence:
  - reference: PMID:33041192
    reference_title: "Screening and diagnosis of acute and chronic bird-related hypersensitivity pneumonitis by serum IgG and IgA antibodies to bird antigens with ImmunoCAP®."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Possible sources of bird antigens are bird breeding, feather products and fertilizer with fowl droppings."
    explanation: The abstract explicitly lists common avian antigen exposure sources.
  - reference: PMID:14503346
    reference_title: "[A case of acute bird fancier's lung caused by feather duvet]."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "She had raised two budgerigars for the last 15 years and had been using a feather duvet for one year."
    explanation: The case report documents direct bird exposure and feather product exposure associated with bird fancier's lung.
  - reference: PMID:1053441
    reference_title: "Pigeon breeders' disease--a prevalence study and review."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Among fifty-three Salt Lake City, Utah area pigeon fanciers, 21% were found to have the clinical picture of pigeon breeders' disease."
    explanation: Pigeon fancier exposure is directly tied to bird fancier's lung in this prevalence study.
  - reference: PMID:39958101
    reference_title: "Advanced Imaging and Occupational History in the Diagnosis of Bird Fancier's Lung: A Case Report."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "immune-mediated interstitial lung disease (ILD) resulting from the repeated inhalation of avian proteins found in bird droppings, feathers, and serum."
    explanation: The case report explicitly identifies avian protein sources (droppings, feathers, serum) as exposure triggers.
  - reference: PMID:33318919
    reference_title: "Bird Fancier's lung: An underdiagnosed etiology of dyspnea."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "triggered by exposure to highly antigenic avian proteins excreted in bird droppings and waxy proteins covering feathers of a variety of birds"
    explanation: The case report details avian protein sources in droppings and feathers as causative exposures.
  - reference: DOI:10.29262/ram.v72i4.1462
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Objective: Case series of patients with domestic hypersensitivity pneumonitis, focusing on hidden avian exposures or other non-suspected antigens (feather comforters and pillows)."
    explanation: The case series highlights feather bedding as hidden avian exposure sources linked to HP.
clinical_trials:
- name: NCT02958917
  phase: PHASE_II
  status: TERMINATED
  description: Randomized, double-blind, placebo-controlled study evaluating pirfenidone in fibrotic hypersensitivity pneumonitis.
  target_phenotypes:
  - preferred_term: Dyspnea
    term:
      id: HP:0002094
      label: Dyspnea
  - preferred_term: Pulmonary fibrosis
    term:
      id: HP:0002206
      label: Pulmonary fibrosis
  evidence:
  - reference: clinicaltrials:NCT02958917
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Patients are being offered participation in this pirfenidone trial because They have been diagnosed with fibrotic hypersensitivity pneumonitis (FHP), a type of interstitial lung disease (ILD)."
    explanation: The registry entry specifies the trial population and disease focus.
- name: NCT02496182
  phase: PHASE_II
  status: UNKNOWN
  description: Study evaluating addition of pirfenidone to prednisone and azathioprine in chronic hypersensitivity pneumonitis with pulmonary fibrosis.
  notes: ClinicalTrials.gov lists Phase 2 and Phase 3 for this study.
  target_phenotypes:
  - preferred_term: Pulmonary fibrosis
    term:
      id: HP:0002206
      label: Pulmonary fibrosis
  - preferred_term: Cough
    term:
      id: HP:0012735
      label: Cough
  evidence:
  - reference: clinicaltrials:NCT02496182
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "the investigators propose to evaluate the addition of Pirfenidone to the actual treatment with Prednisone and Azathioprine in the treatment of patients with Pulmonary Fibrosis secondary to a Chronic Hypersensitivity Pneumonitis."
    explanation: The registry summary outlines treatment strategy and target population.
- name: NCT04844359
  phase: NOT_APPLICABLE
  status: ACTIVE_NOT_RECRUITING
  description: Observational study developing and validating a prognostic blood transcriptomic signature in chronic hypersensitivity pneumonitis.
  target_phenotypes:
  - preferred_term: Pulmonary fibrosis
    term:
      id: HP:0002206
      label: Pulmonary fibrosis
  - preferred_term: Dyspnea
    term:
      id: HP:0002094
      label: Dyspnea
  evidence:
  - reference: clinicaltrials:NCT04844359
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Up to 150 patients with hypersensitivity pneumonitis will be enrolled at 7 clinical centers across the United States. Patients will be followed for 24 months to determine if biomarkers in the blood can predict disease progression."
    explanation: The registry summary describes enrollment and biomarker-focused outcomes.
animal_models:
- species: Mus musculus
  description: Mouse model sensitized with pigeon serum and challenged intranasally to induce bird-related hypersensitivity pneumonitis.
  evidence:
  - reference: DOI:10.3390/ijms24032884
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "On days −3 and −1, mice were intraperitoneally sensitized with commercial pigeon serum (PS) or saline. Intranasal instillations with PS or saline were carried out on three consecutive days/week over either 3 weeks (Group 1) or 12 weeks (Group 2)."
    explanation: The study describes a pigeon serum-induced mouse model of BRHP.
- species: Mus musculus
  description: Pigeon breeder's lung model generated by tracheal instillation of pigeon dropping extract protein powder.
  evidence:
  - reference: PMID:39844643
    reference_title: "Immunopathological characteristics and therapeutic effects of UC-MSCs in a pigeon breeder's lung mouse model."
    supports: SUPPORT
    evidence_source: MODEL_ORGANISM
    snippet: "PBL models are created in A/J mice through tracheal instillation of pigeon dropping extract (PDE) protein powder."
    explanation: The study establishes a pigeon breeder's lung mouse model using pigeon dropping extract.
datasets:
- accession: geo:GSE150910
  title: "RNA-Sequencing of Chronic hypersensitivity pneumonitis compared with Idiopathic Pulmonary Fibrosis and Control Lung"
  description: Bulk RNA-seq of whole lung tissue from chronic hypersensitivity pneumonitis, idiopathic pulmonary fibrosis, and control samples.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: BULK_RNA_SEQ
  sample_types:
  - preferred_term: lung tissue
    tissue_term:
      preferred_term: lung
      term:
        id: UBERON:0002048
        label: lung
  conditions:
  - hypersensitivity pneumonitis
  - idiopathic pulmonary fibrosis
  - normal lung
  publication: PMID:32602730
  evidence:
  - reference: PMID:32602730
    reference_title: "Chronic Hypersensitivity Pneumonitis, an Interstitial Lung Disease with Distinct Molecular Signatures."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Transcriptome analysis of lung samples from CHP (n = 82), IPF (n = 103), and unaffected controls (n = 103) was conducted."
    explanation: The study reports bulk transcriptome profiling of lung samples from chronic HP, IPF, and controls, matching the dataset description.
  notes: GEO record includes HP, IPF, and control whole-lung RNA-seq samples.
- accession: geo:GSE271789
  title: "Single-Cell Analysis Reveals Novel Immune Perturbations in Fibrotic Hypersensitivity Pneumonitis"
  description: Single-cell and single-nucleus RNA-seq of PBMCs and BAL cells from fibrotic hypersensitivity pneumonitis, idiopathic pulmonary fibrosis, and controls.
  organism:
    preferred_term: human
    term:
      id: NCBITaxon:9606
      label: Homo sapiens
  data_type: SINGLE_CELL_RNA_SEQ
  sample_types:
  - preferred_term: peripheral blood mononuclear cell
    cell_type_term:
      preferred_term: peripheral blood mononuclear cell
      term:
        id: CL:2000001
        label: peripheral blood mononuclear cell
  - preferred_term: bronchoalveolar lavage
    tissue_term:
      preferred_term: lung
      term:
        id: UBERON:0002048
        label: lung
  conditions:
  - fibrotic hypersensitivity pneumonitis
  - idiopathic pulmonary fibrosis
  - healthy control
  publication: PMID:38924775
  evidence:
  - reference: PMID:38924775
    reference_title: "Single-Cell Analysis Reveals Novel Immune Perturbations in Fibrotic Hypersensitivity Pneumonitis."
    supports: SUPPORT
    evidence_source: HUMAN_CLINICAL
    snippet: "Single-cell 5' RNA sequencing was conducted on peripheral blood mononuclear cells and BAL cells obtained from 45 patients with FHP, 63 patients with idiopathic pulmonary fibrosis (IPF), 4 patients with nonfibrotic hypersensitivity pneumonitis, and 36 healthy control subjects in the United States and Mexico."
    explanation: The abstract documents single-cell sequencing of PBMC and BAL cells from fibrotic HP, IPF, and controls, aligning with the dataset.
  notes: GEO record linked to AJRCCM 2024 single-cell study profiling PBMC and BAL.
references:
- reference: DOI:10.1371/journal.pone.0273544
  title: Impact of number and type of identified antigen on transplant-free survival in hypersensitivity pneumonitis
  found_in:
  - Bird_Fanciers_Lung-deep-research-falcon.md
  findings:
  - statement: Identification of inciting antigen can affect diagnostic confidence, quality of life, and prognosis in patients with HP.
    supporting_text: Identification of inciting antigen can affect diagnostic confidence, quality of life, and prognosis in patients with HP.
    evidence:
    - reference: DOI:10.1371/journal.pone.0273544
      reference_title: Impact of number and type of identified antigen on transplant-free survival in hypersensitivity pneumonitis
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Identification of inciting antigen can affect diagnostic confidence, quality of life, and prognosis in patients with HP.
      explanation: Deep research cited this publication as relevant literature for Bird Fanciers Lung.
- reference: DOI:10.21203/rs.3.rs-5418767/v1
  title: Evaluation of clinical and radiological features of patients diagnosed with hypersensitivity pneumonia
  found_in:
  - Bird_Fanciers_Lung-deep-research-falcon.md
  findings:
  - statement: Hypersensitivity pneumonitis (HP) is an inflammatory fibrotic disease that affects the lung parenchyma and small airways.
    supporting_text: Hypersensitivity pneumonitis (HP) is an inflammatory fibrotic disease that affects the lung parenchyma and small airways.
    evidence:
    - reference: DOI:10.21203/rs.3.rs-5418767/v1
      reference_title: Evaluation of clinical and radiological features of patients diagnosed with hypersensitivity pneumonia
      supports: SUPPORT
      evidence_source: OTHER
      snippet: Hypersensitivity pneumonitis (HP) is an inflammatory fibrotic disease that affects the lung parenchyma and small airways.
      explanation: Deep research cited this publication as relevant literature for Bird Fanciers Lung.
- reference: DOI:10.3390/diagnostics15243137
  title: 'Fibrotic Patterns and Diagnostic Correlates in Hypersensitivity Pneumonitis: Clinical, Radiologic, and Hematologic Insights'
  found_in:
  - Bird_Fanciers_Lung-deep-research-falcon.md
  findings:
  - statement: Hypersensitivity pneumonitis (HP) is an interstitial lung disease characterized by immune-mediated inflammation and variable degrees of fibrosis.
    supporting_text: Hypersensitivity pneumonitis (HP) is an interstitial lung disease characterized by immune-mediated inflammation and variable degrees of fibrosis.
    evidence:
    - reference: DOI:10.3390/diagnostics15243137
      reference_title: 'Fibrotic Patterns and Diagnostic Correlates in Hypersensitivity Pneumonitis: Clinical, Radiologic, and Hematologic Insights'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Hypersensitivity pneumonitis (HP) is an interstitial lung disease characterized by immune-mediated inflammation and variable degrees of fibrosis.
      explanation: Deep research cited this publication as relevant literature for Bird Fanciers Lung.
- reference: DOI:10.3390/ijtm4020025
  title: 'The Role of Serum IgG Precipitins against Six Typical Organic Antigens Involved in Hypersensitivity Pneumonitis: A 10-Year Retrospective Study of a Referral Interstitial Lung Disease Centre'
  found_in:
  - Bird_Fanciers_Lung-deep-research-falcon.md
  findings:
  - statement: Hypersensitivity pneumonitis (HP) represents the third common interstitial lung disease caused by an exaggerated immune response following the inhalation of organic and/or chemical environmental antigens.
    supporting_text: Hypersensitivity pneumonitis (HP) represents the third common interstitial lung disease caused by an exaggerated immune response following the inhalation of organic and/or chemical environmental antigens.
    evidence:
    - reference: DOI:10.3390/ijtm4020025
      reference_title: 'The Role of Serum IgG Precipitins against Six Typical Organic Antigens Involved in Hypersensitivity Pneumonitis: A 10-Year Retrospective Study of a Referral Interstitial Lung Disease Centre'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Hypersensitivity pneumonitis (HP) represents the third common interstitial lung disease caused by an exaggerated immune response following the inhalation of organic and/or chemical environmental antigens.
      explanation: Deep research cited this publication as relevant literature for Bird Fanciers Lung.
- reference: DOI:10.3390/jcm13175074
  title: Does a Type of Inciting Antigen Correlate with the Presence of Lung Fibrosis in Patients with Hypersensitivity Pneumonitis?
  found_in:
  - Bird_Fanciers_Lung-deep-research-falcon.md
  findings:
  - statement: Hypersensitivity pneumonitis (HP) is an interstitial inflammatory lung disease that develops as a result of exposition to various, mostly organic antigens.
    supporting_text: Hypersensitivity pneumonitis (HP) is an interstitial inflammatory lung disease that develops as a result of exposition to various, mostly organic antigens.
    evidence:
    - reference: DOI:10.3390/jcm13175074
      reference_title: Does a Type of Inciting Antigen Correlate with the Presence of Lung Fibrosis in Patients with Hypersensitivity Pneumonitis?
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Hypersensitivity pneumonitis (HP) is an interstitial inflammatory lung disease that develops as a result of exposition to various, mostly organic antigens.
      explanation: Deep research cited this publication as relevant literature for Bird Fanciers Lung.
- reference: DOI:10.3390/jcm8010014
  title: 'Effects of Corticosteroid Treatment and Antigen Avoidance in a Large Hypersensitivity Pneumonitis Cohort: A Single-Centre Cohort Study'
  found_in:
  - Bird_Fanciers_Lung-deep-research-falcon.md
  findings:
  - statement: Although the third most frequent interstitial lung disease, hypersensitivity pneumonitis (HP) remains an enigmatic disease without clear diagnostic and therapeutic guidelines.
    supporting_text: Although the third most frequent interstitial lung disease, hypersensitivity pneumonitis (HP) remains an enigmatic disease without clear diagnostic and therapeutic guidelines.
    evidence:
    - reference: DOI:10.3390/jcm8010014
      reference_title: 'Effects of Corticosteroid Treatment and Antigen Avoidance in a Large Hypersensitivity Pneumonitis Cohort: A Single-Centre Cohort Study'
      supports: SUPPORT
      evidence_source: HUMAN_CLINICAL
      snippet: Although the third most frequent interstitial lung disease, hypersensitivity pneumonitis (HP) remains an enigmatic disease without clear diagnostic and therapeutic guidelines.
      explanation: Deep research cited this publication as relevant literature for Bird Fanciers Lung.

📚

References & Deep Research

References

6

DOI:10.1371/journal.pone.0273544

Impact of number and type of identified antigen on transplant-free survival in hypersensitivity pneumonitis

1 finding

Identification of inciting antigen can affect diagnostic confidence, quality of life, and prognosis in patients with HP.

"Identification of inciting antigen can affect diagnostic confidence, quality of life, and prognosis in patients with HP."

Show evidence (1 reference)

DOI:10.1371/journal.pone.0273544 SUPPORT Human Clinical

"Identification of inciting antigen can affect diagnostic confidence, quality of life, and prognosis in patients with HP."

Deep research cited this publication as relevant literature for Bird Fanciers Lung.

DOI:10.21203/rs.3.rs-5418767/v1

Evaluation of clinical and radiological features of patients diagnosed with hypersensitivity pneumonia

1 finding

Hypersensitivity pneumonitis (HP) is an inflammatory fibrotic disease that affects the lung parenchyma and small airways.

"Hypersensitivity pneumonitis (HP) is an inflammatory fibrotic disease that affects the lung parenchyma and small airways."

Show evidence (1 reference)

DOI:10.21203/rs.3.rs-5418767/v1 SUPPORT Other

"Hypersensitivity pneumonitis (HP) is an inflammatory fibrotic disease that affects the lung parenchyma and small airways."

Deep research cited this publication as relevant literature for Bird Fanciers Lung.

DOI:10.3390/diagnostics15243137

Fibrotic Patterns and Diagnostic Correlates in Hypersensitivity Pneumonitis: Clinical, Radiologic, and Hematologic Insights

1 finding

Hypersensitivity pneumonitis (HP) is an interstitial lung disease characterized by immune-mediated inflammation and variable degrees of fibrosis.

"Hypersensitivity pneumonitis (HP) is an interstitial lung disease characterized by immune-mediated inflammation and variable degrees of fibrosis."

Show evidence (1 reference)

DOI:10.3390/diagnostics15243137 SUPPORT Human Clinical

"Hypersensitivity pneumonitis (HP) is an interstitial lung disease characterized by immune-mediated inflammation and variable degrees of fibrosis."

Deep research cited this publication as relevant literature for Bird Fanciers Lung.

DOI:10.3390/ijtm4020025

The Role of Serum IgG Precipitins against Six Typical Organic Antigens Involved in Hypersensitivity Pneumonitis: A 10-Year Retrospective Study of a Referral Interstitial Lung Disease Centre

1 finding

Hypersensitivity pneumonitis (HP) represents the third common interstitial lung disease caused by an exaggerated immune response following the inhalation of organic and/or chemical environmental antigens.

"Hypersensitivity pneumonitis (HP) represents the third common interstitial lung disease caused by an exaggerated immune response following the inhalation of organic and/or chemical environmental antigens."

Show evidence (1 reference)

DOI:10.3390/ijtm4020025 SUPPORT Human Clinical

"Hypersensitivity pneumonitis (HP) represents the third common interstitial lung disease caused by an exaggerated immune response following the inhalation of organic and/or chemical environmental antigens."

Deep research cited this publication as relevant literature for Bird Fanciers Lung.

DOI:10.3390/jcm13175074

Does a Type of Inciting Antigen Correlate with the Presence of Lung Fibrosis in Patients with Hypersensitivity Pneumonitis?

1 finding

Hypersensitivity pneumonitis (HP) is an interstitial inflammatory lung disease that develops as a result of exposition to various, mostly organic antigens.

"Hypersensitivity pneumonitis (HP) is an interstitial inflammatory lung disease that develops as a result of exposition to various, mostly organic antigens."

Show evidence (1 reference)

DOI:10.3390/jcm13175074 SUPPORT Human Clinical

"Hypersensitivity pneumonitis (HP) is an interstitial inflammatory lung disease that develops as a result of exposition to various, mostly organic antigens."

Deep research cited this publication as relevant literature for Bird Fanciers Lung.

DOI:10.3390/jcm8010014

Effects of Corticosteroid Treatment and Antigen Avoidance in a Large Hypersensitivity Pneumonitis Cohort: A Single-Centre Cohort Study

1 finding

Although the third most frequent interstitial lung disease, hypersensitivity pneumonitis (HP) remains an enigmatic disease without clear diagnostic and therapeutic guidelines.

"Although the third most frequent interstitial lung disease, hypersensitivity pneumonitis (HP) remains an enigmatic disease without clear diagnostic and therapeutic guidelines."

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DOI:10.3390/jcm8010014 SUPPORT Human Clinical

"Although the third most frequent interstitial lung disease, hypersensitivity pneumonitis (HP) remains an enigmatic disease without clear diagnostic and therapeutic guidelines."

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Bird Fancier’s Lung (BFL) / Avian Hypersensitivity Pneumonitis (HP): Disease Characteristics Research Report

Edison Scientific Literature 32 citations 2026-05-08T08:54:21.443720

Bird Fancier’s Lung (BFL) / Avian Hypersensitivity Pneumonitis (HP): Disease Characteristics Research Report

Executive summary (current understanding)

Bird fancier’s lung (BFL) is a form of hypersensitivity pneumonitis (HP)—an immune-mediated interstitial lung disease triggered by inhalation of avian-derived antigens (e.g., from live birds, feathers, droppings, and feather-containing bedding). Contemporary practice frameworks classify HP into non-fibrotic and fibrotic phenotypes based primarily on HRCT and/or pathology, because fibrosis strongly influences prognosis and treatment response. Recent (2023–2024) research emphasizes (i) structured exposure assessment, (ii) integration of HRCT + BAL lymphocytosis + serology (antigen-specific IgG/“precipitins”), and (iii) longitudinal monitoring approaches such as serial anti-pigeon IgG testing to infer ongoing exposure and track lung-function decline in fibrotic avian HP. (deutsch2024doesatype pages 2-4, akkurt2024evaluationofclinical pages 1-4, okuda2024longitudinalchangesin pages 1-2)

1. Disease information

1.1 Overview/definition

HP is described as “an interstitial inflammatory lung disease that develops as a result of exposition to various, mostly organic antigens” and can be subdivided into fibrotic and non-fibrotic forms. (deutsch2024doesatype pages 2-4)

BFL specifically refers to HP caused by exposure to bird-related antigens. In a high-confidence HP cohort, avian antigen exposure was operationalized as “regular exposure to a live bird or feather products,” reflecting real-world BFL exposure settings (bird ownership, bird breeding, feather bedding/down products). (kypreos2022impactofnumber pages 1-2)

1.2 Key identifiers (ICD/MeSH/MONDO/Orphanet)

The present tool-based literature retrieval did not return authoritative ontology/coding records (e.g., MeSH descriptor page, ICD-10/ICD-11 entry, MONDO, Orphanet) that can be directly cited. Therefore, standardized identifiers are not populated here to avoid uncited claims.

1.3 Synonyms / alternative names

Within the retrieved clinical/review literature, BFL is used in the context of “avian” HP and “bird-related” HP, and “feather” exposure is treated as a clinically important inciting antigen category. (kypreos2022impactofnumber pages 1-2)

1.4 Evidence sources

This report primarily reflects aggregated disease-level evidence from retrospective cohorts and diagnostic-method papers (with some prospective/longitudinal follow-up), rather than individual EHR case reports. (deutsch2024doesatype pages 2-4, akkurt2024evaluationofclinical pages 1-4, okuda2024longitudinalchangesin pages 1-2)

2. Etiology

2.1 Disease causal factors

Primary causal factor: inhalation exposure to bird-related antigens (live birds, feathers/down products, droppings; sometimes quantified indirectly by antigen-specific IgG). Avian exposure is among the most prevalent HP exposures in contemporary cohorts. (deutsch2024doesatype pages 2-4, akkurt2024evaluationofclinical pages 1-4)

Recent cohort evidence (2024): In a 2019–2023 HP cohort (n=66), avian antigen exposure was one of the most prevalent exposures and was more common among fibrotic HP than non-fibrotic HP in univariate comparisons (70% vs 40%). (deutsch2024doesatype pages 9-10)

2.2 Risk factors

Environmental/occupational risk factors

Bird/bird-product exposure dominates identified exposures in some real-world ILD-center populations: in a 2020–2024 HP cohort (n=100), 65% had identifiable exposure, and “86.4% of all known exposures were caused by exposure to birds and bird products.” (akkurt2024evaluationofclinical pages 1-4)
Co-exposures may contribute to fibrotic phenotype in HP broadly; in the 2019–2023 cohort, avian exposure and coal/biomass heating were more prevalent among fibrotic HP than non-fibrotic HP, but older age was the only independent predictor of fibrotic HP in multivariable analysis. (deutsch2024doesatype pages 9-10)

Genetic susceptibility (host factors)

Multiple sources emphasize that host susceptibility modifies who develops fibrotic HP, but the retrieved evidence did not provide validated single-gene causal variants specific to BFL. For example, the 2024 cohort paper notes “genetic susceptibility… may influence the fibrotic process,” but does not specify causal genes/variants. (deutsch2024doesatype pages 9-10)

2.3 Protective factors

Direct, well-quantified protective factors (genetic or environmental) specific to BFL were not identified in the retrieved evidence.

2.4 Gene–environment interactions

The retrieved evidence supports a gene/environment framework (susceptible host + antigen exposure) but does not provide specific gene–environment interaction loci for BFL. (deutsch2024doesatype pages 9-10)

3. Phenotypes (clinical presentation)

3.1 Core clinical phenotypes (with suggested HPO terms)

The retrieved studies primarily characterize HP/BFL via exposure history, lung imaging, BAL profile, and lung-function decline rather than symptom prevalence counts. Key disease manifestations that can be mapped to HPO include:

Dyspnea/shortness of breath (HP:0002094) (inferred as a core ILD manifestation; outcomes include SOBQ in trials) (NCT02496182 chunk 1)
Cough (HP:0012735) (typical ILD symptom; not quantified in retrieved excerpts)
Reduced forced vital capacity / restrictive physiology (HP:0033280 “Abnormal lung function test” / or use LOINC mapping for FVC) (okuda2024longitudinalchangesin pages 1-2)
Reduced diffusing capacity / DLCO abnormality (HP:0002091 “Decreased diffusing capacity of lung for carbon monoxide”) (sadeleer2018effectsofcorticosteroid pages 6-8)
Imaging phenotypes consistent with HP:
Ground-glass opacities (HPO does not directly encode CT patterns; use radiology ontology in implementation)
Centrilobular nodules
Air trapping / mosaic attenuation / “three-density sign”
Fibrosis features: reticulation, traction bronchiectasis, honeycombing, reduced lung volumes (deutsch2024doesatype pages 2-4, akkurt2024evaluationofclinical pages 1-4)

3.2 Phenotype characteristics: fibrotic vs non-fibrotic

Modern cohorts apply a phenotype split that is prognostically meaningful: - In a 2018 cohort (n=202), fibrotic HP had substantially worse prognosis with median survival 9.2 years, while non-fibrotic HP had “excellent survival” (median not reached). (sadeleer2018effectsofcorticosteroid pages 1-3, sadeleer2018effectsofcorticosteroid pages 3-6)

3.3 Frequency and real-world distributions from recent studies

HRCT findings (2020–2024 cohort, n=100): reticulation 87%, ground-glass opacities 84.7%, centrilobular nodules 75%, and fibrotic features 40%. (akkurt2024evaluationofclinical pages 1-4)

3.4 Quality of life (QoL) impact

QoL impairment is inferred from use of validated QoL and dyspnea measures in chronic HP trials (e.g., SGRQ, SOBQ, EQ-5D). (NCT02496182 chunk 1)

4. Genetic / molecular information

4.1 Causal genes

No monogenic causal genes for BFL were supported by the retrieved evidence.

4.2 Biomarkers and molecular tests (2023–2024 emphasis)

Antigen-specific IgG (“precipitins”)

Key concept: antigen-specific IgG supports exposure/sensitization assessment but is not sufficient alone to confirm or exclude HP.

2024 development—longitudinal serology: A 2024 longitudinal cohort of fibrotic avian HP (n=28) found that annual changes in anti-pigeon IgG correlate with changes in FVC: ELISA r = −0.6221 (p<0.001) and ImmunoCAP r = −0.4302 (p=0.022); multiple regression retained significant associations (p=0.012 and p=0.015). The abstract states: “the annual changes in serum IgG antibody titers… correlated with FVC changes.” (okuda2024longitudinalchangesin pages 1-2)

2024 diagnostic serology cutoffs: A 10-year retrospective study (54 HP cases; 1516 controls) using a population-derived 97.5th percentile control cutoff reported that 30/54 (56%) HP patients had ≥1 positive IgG precipitin; pigeon-dropping IgG was the most frequent positive, and cutoff values were explicitly reported (e.g., pigeon droppings 62.4 mg/L). (intra2024theroleof pages 1-2, intra2024theroleof pages 5-6)

5. Environmental information

5.1 Environmental determinants and exposure sources

BFL/avian HP exposures include: - Live birds and bird breeding/keeping, with sustained exposure duration in many patients (e.g., 19/28 had kept birds >6 months in one fibrotic avian HP cohort). (okuda2024longitudinalchangesin pages 1-2) - Feather/down products (e.g., feather bedding); these are clinically relevant enough that “feather exposure should be considered an inciting antigen in patients with ILD.” (kypreos2022impactofnumber pages 1-2)

5.2 Lifestyle factors

Smoking and other lifestyle factors were not systematically extractable from the cited evidence snippets; thus, they are not summarized with statistics here.

5.3 Infectious agents

No specific infectious agent etiology is supported; BFL is characterized as an immune response to inhaled antigens rather than infection. (deutsch2024doesatype pages 2-4)

6. Mechanism / pathophysiology

6.1 Current mechanistic model (causal chain)

1) Repeated inhalation of bird-related antigens → 2) immune sensitization and immune-mediated alveolitis (often with BAL lymphocytosis) → 3) granulomatous/interstitial inflammation and small-airway involvement → 4) in some individuals, progression to lung fibrosis (fibrotic HP) with worsening restrictive physiology and impaired gas exchange. This broad chain is consistent with modern descriptions that HP is “characterized by immune-mediated inflammation and variable degrees of fibrosis.” (akkurt2024evaluationofclinical pages 1-4)

6.2 Immune system involvement and key processes (ontology suggestions)

Suggested GO biological process terms (implementation suggestions): - GO:0006954 inflammatory response - GO:0002250 adaptive immune response - GO:0006950 response to stress - GO:0042110 T cell activation - GO:0001817 regulation of cytokine production - GO:0043062 extracellular matrix organization (fibrotic phenotype)

Suggested Cell Ontology (CL) cell types: - CL:0000583 alveolar macrophage - CL:0000084 T cell - CL:0000236 B cell - CL:0000542 lymphocyte - CL:0000182 neutrophil (noting exploratory blood-count associations with HRCT fibrosis features in a 2020–2024 cohort) (akkurt2024evaluationofclinical pages 1-4)

6.3 Recent mechanistic/biomarker angle: exposure persistence and serology

Serial anti-pigeon IgG change plausibly reflects ongoing/recurrent antigen exposure and is statistically linked to annual FVC decline in fibrotic avian HP, providing a mechanistically grounded monitoring concept (antigen exposure burden ↔ immune response intensity ↔ disease progression). (okuda2024longitudinalchangesin pages 1-2, okuda2024longitudinalchangesin pages 7-8)

7. Anatomical structures affected

7.1 Organ and tissue level (UBERON suggestions)

Primary: lung (UBERON:0002048), pulmonary alveolus (UBERON:0002299), bronchiole/small airways (UBERON:0002180).

The clinical characterization explicitly describes involvement of “lung parenchyma and small airways.” (akkurt2024evaluationofclinical pages 1-4)

8. Temporal development

8.1 Onset and course

HP includes non-fibrotic and fibrotic phenotypes with different clinical trajectories. Fibrotic disease course is associated with chronicity and worse outcomes, while non-fibrotic HP may show physiologic improvement with corticosteroids and exposure avoidance. (sadeleer2018effectsofcorticosteroid pages 1-3, sadeleer2018effectsofcorticosteroid pages 3-6)

9. Inheritance and population

9.1 Epidemiology

The retrieved evidence base did not contain population-level incidence/prevalence rates specific to BFL (e.g., cases per 100,000). Therefore epidemiologic rates are not provided here.

9.2 Population demographics and distributions (from available cohorts)

Example cohort demographics for fibrotic avian HP (Japan, 2024): mean age 64.5 years, mean FVC 85.3% predicted. (okuda2024longitudinalchangesin pages 1-2)
Sex distribution varies by cohort; one HP cohort had “equal sex distribution.” (akkurt2025fibroticpatternsand pages 12-12)

10. Diagnostics

10.1 Key diagnostic concepts (current practice)

Diagnosis is integrative, typically combining: - Exposure assessment (semi-structured questionnaires) (deutsch2024doesatype pages 2-4) - HRCT pattern classification (fibrotic vs non-fibrotic features and small-airway signs) (deutsch2024doesatype pages 2-4) - BAL cellular analysis (lymphocytosis as supportive evidence) (deutsch2024doesatype pages 2-4) - Serology (antigen-specific IgG/precipitins for relevant antigens) (deutsch2024doesatype pages 2-4, intra2024theroleof pages 1-2) - Histopathology in selected cases (e.g., surgical lung biopsy or cryobiopsy) (okuda2024longitudinalchangesin pages 1-2) - Inhalation challenge testing in specialized settings (e.g., pasteurized pigeon egg solution protocol in a fibrotic avian HP cohort) (okuda2024longitudinalchangesin pages 2-4)

10.2 Recent diagnostic data points

BAL lymphocytosis: in the 2019–2023 cohort, median BAL lymphocytes were 38.8% (IQR 26.9–52.6). (deutsch2024doesatype pages 2-4)
HRCT: fibrotic HP definition included reticular opacities, traction bronchiectasis, reduced lung volume, honeycombing, plus small-airway findings (centrilobular nodules, ground-glass, air trapping, three-density sign). (deutsch2024doesatype pages 2-4)
Serology cutoffs (example panel, 2024): pigeon droppings IgG cutoff 62.4 mg/L (97.5th percentile controls) and other antigen cutoffs (Penicillium 71.0 mg/L; Aspergillus fumigatus 61.8 mg/L; Alternaria 35.3 mg/L; Aspergillus niger 44.3 mg/L; Micropolyspora faeni 20.5 mg/L). (intra2024theroleof pages 5-6)

10.3 Differential diagnosis

The retrieved excerpts did not provide a structured differential diagnosis list. In practice, major differentials for fibrotic HP include idiopathic pulmonary fibrosis and connective tissue disease–associated ILD; however, these statements are not expanded here without direct supporting excerpts.

11. Outcome / prognosis

11.1 Prognostic strata: fibrotic vs non-fibrotic

Fibrosis is a major determinant of prognosis: - In a 2018 cohort, fibrotic HP median survival was 9.2 years and fibrotic vs non-fibrotic HP carried HR 4.35 (95% CI 2.22–8.33). (sadeleer2018effectsofcorticosteroid pages 3-6)

11.2 Antigen identification and outcomes (real-world prognostic implications)

In a high-confidence chronic HP cohort (n=136), identification of an inciting antigen by clinical history was independently associated with better transplant-free survival (HR 0.39, 95% CI 0.17–0.89). Median transplant-free survival was 4.89 years with no antigen identified vs 12.8 years with one identified antigen; feather exposure had HR 0.30 vs no antigen (95% CI 0.10–0.96). (kypreos2022impactofnumber pages 4-5, kypreos2022impactofnumber pages 5-7)

12. Treatment

12.1 Core management principle: exposure remediation/avoidance

Exposure avoidance is a cornerstone intervention: - In non-fibrotic HP, avoidance was associated with improved lung-function trajectory (FVC from −0.24%/month to +0.92%/month, p=0.016; DLCO from −0.23%/month to +0.37%/month with an immediate +4.0% increase, p=0.04). (sadeleer2018effectsofcorticosteroid pages 6-8)

Suggested MAXO terms (implementation suggestions): - MAXO:0000527 “avoidance of allergen exposure” (or nearest available allergen/antigen avoidance term) - MAXO:0000499 “environmental intervention”

12.2 Corticosteroids and immunosuppression

In the same large cohort, corticosteroids improved physiology in non-fibrotic HP (e.g., FVC from −0.35%/month to +0.84%/month after steroids, p<0.001) but showed no physiologic benefit in fibrotic HP and no survival benefit overall. (sadeleer2018effectsofcorticosteroid pages 3-6)

Suggested MAXO terms: - systemic glucocorticoid therapy - immunosuppressive therapy (e.g., azathioprine in some trial protocols) (NCT02496182 chunk 1)

12.3 Antifibrotics and clinical trials (real-world implementation and ongoing evidence)

Because fibrotic HP can behave like progressive pulmonary fibrosis, antifibrotic strategies have been studied in HP-specific and broader PPF settings.

Pirfenidone trials in chronic/fibrotic HP (ClinicalTrials.gov): - NCT02958917 (posted 2017; terminated during COVID-19): randomized, double-blind trial in fibrotic HP; pirfenidone 2403 mg/day vs placebo for 52 weeks; primary endpoint = change in % predicted FVC at week 52; key inclusion included multidisciplinary-consensus fibrotic HP, age 18–80, FVC ≥40%, DLCO ≥30%. URL: https://clinicaltrials.gov/study/NCT02958917 (NCT02958917 chunk 1, NCT02958917 chunk 2) - NCT04675619 (start 2019; completed): progressive chronic HP with >10% fibrosis on HRCT and absolute FVC decline >5% in prior 6 months; pirfenidone + standard care vs standard care; endpoints included FVC and 6MWD at 6 months. URL: https://clinicaltrials.gov/study/NCT04675619 (NCT04675619 chunk 1)

Suggested MAXO terms: - antifibrotic therapy - pirfenidone treatment

13. Prevention

Primary prevention is largely exposure-based: minimizing/avoiding inhalation of bird-derived antigens and feather/down exposure in susceptible individuals or in settings where symptoms have occurred. Prognostic evidence supports that identifying an inciting antigen is associated with improved transplant-free survival, reinforcing prevention via exposure identification/remediation. (kypreos2022impactofnumber pages 5-7)

14. Other species / natural disease

No tool-retrieved evidence in this run addressed naturally occurring BFL-like disease in non-human species or zoonotic transmission.

15. Model organisms

No tool-retrieved evidence in this run described specific model organisms for BFL/avian HP. (General HP models exist in the literature, but are not summarized here without direct citations.)

Recent developments (2023–2024) highlighted

1) Longitudinal serology as disease monitoring in fibrotic avian HP: serial anti-pigeon IgG (ELISA/ImmunoCAP) correlates with FVC decline (Okuda 2024). (okuda2024longitudinalchangesin pages 1-2, okuda2024longitudinalchangesin pages 2-4) 2) Population-derived precipitin cutoffs and antigen-panel optimization: large control dataset used to define 97.5th percentile cutoffs for common antigens including pigeon droppings (Intra 2024). (intra2024theroleof pages 1-2, intra2024theroleof pages 5-6) 3) Modern cohort quantification of exposure patterns and HRCT findings: bird/bird-product exposures dominate identified exposures in a tertiary cohort and HRCT frequencies are quantified (Akkurt 2024). (akkurt2024evaluationofclinical pages 1-4)

Structured evidence table

The following table summarizes high-yield, tool-retrieved evidence most relevant to a BFL knowledge-base entry.

Topic	Key finding	Study (author year journal)	Population/design	URL/DOI	Citation
Exposure	In a 2024 HP cohort, 94% reported at least one exposure; avian exposure was more common in fibrotic vs non-fibrotic HP (70% vs 40%, p=0.03), though older age was the only independent predictor of fibrosis.	Deutsch et al. 2024, Journal of Clinical Medicine	Retrospective cohort, 66 HP patients diagnosed 2019-2023	https://doi.org/10.3390/jcm13175074	(deutsch2024doesatype pages 2-4)
Exposure	In a 2024 tertiary-center HP cohort, 65% had identifiable exposure and 86.4% of known exposures were birds/bird products.	Akkurt et al. 2024, preprint	Retrospective cross-sectional study, 100 HP patients (2020-2024)	https://doi.org/10.21203/rs.3.rs-5418767/v1	(akkurt2024evaluationofclinical pages 1-4)
Diagnosis	Median BAL lymphocyte proportion was 38.8% (IQR 26.9-52.6) in the 2024 cohort; fibrotic HP was classified by CT fibrosis (reticulation, traction bronchiectasis, reduced volume, honeycombing) plus small-airway findings.	Deutsch et al. 2024, Journal of Clinical Medicine	Retrospective cohort, 66 HP patients	https://doi.org/10.3390/jcm13175074	(deutsch2024doesatype pages 2-4)
Diagnosis	Common HRCT findings in HP were reticulation 87%, ground-glass opacities 84.7%, and centrilobular nodules 75%; fibrotic features were present in 40%.	Akkurt et al. 2024, preprint	Retrospective cross-sectional study, 100 HP patients	https://doi.org/10.21203/rs.3.rs-5418767/v1	(akkurt2024evaluationofclinical pages 1-4)
Biomarkers	Serial anti-pigeon IgG correlated with lung-function decline in fibrotic avian HP: annual IgG change vs relative FVC change, ELISA r=-0.6221 (p<0.001), ImmunoCAP r=-0.4302 (p=0.022); multiple regression remained significant (p=0.012 and p=0.015).	Okuda et al. 2024, BMC Pulmonary Medicine	Longitudinal cohort, 28 fibrotic avian HP patients	https://doi.org/10.1186/s12890-024-03063-0	(okuda2024longitudinalchangesin pages 1-2, okuda2024longitudinalchangesin pages 2-4)
Biomarkers	Using 97.5th-percentile control cutoffs, 30/54 HP patients (56%) had ≥1 positive precipitin; pigeon-dropping IgG was the most frequent positive, with 23/30 positive cases showing elevated pigeon-dropping IgG.	Intra et al. 2024, International Journal of Translational Medicine	10-year retrospective study; 54 HP cases, 1516 controls	https://doi.org/10.3390/ijtm4020025	(intra2024theroleof pages 4-5, intra2024theroleof pages 1-2, intra2024theroleof pages 5-6)
Prognosis	Identification of an inciting antigen independently predicted better transplant-free survival (HR 0.39, 95% CI 0.17-0.89, p=0.025). No-antigen group had median transplant-free survival 4.89 years vs 12.8 years for one identified antigen; feather exposure HR 0.30 vs no antigen (95% CI 0.10-0.96, p=0.043).	Kypreos et al. 2022, PLoS ONE	Retrospective cohort, 136 high/definite chronic HP patients	https://doi.org/10.1371/journal.pone.0273544	(kypreos2022impactofnumber pages 4-5, kypreos2022impactofnumber pages 5-7)
Prognosis	Fibrotic HP had markedly worse outcomes than non-fibrotic HP: median survival 9.2 years in fibrotic HP, while median survival was not reached in non-fibrotic HP; HR for fibrotic vs non-fibrotic HP 4.35 (95% CI 2.22-8.33, p<0.001).	De Sadeleer et al. 2018, Journal of Clinical Medicine	Single-center cohort, 202 HP patients (109 fibrotic, 93 non-fibrotic)	https://doi.org/10.3390/jcm8010014	(sadeleer2018effectsofcorticosteroid pages 1-3, sadeleer2018effectsofcorticosteroid pages 3-6)
Treatment	Corticosteroids improved physiology in non-fibrotic HP but not fibrotic HP; in non-fibrotic HP, FVC changed from -0.35%/month pre-treatment to +0.84%/month after steroid initiation (p<0.001). No survival benefit from corticosteroids was observed.	De Sadeleer et al. 2018, Journal of Clinical Medicine	Single-center cohort, 202 HP patients	https://doi.org/10.3390/jcm8010014	(sadeleer2018effectsofcorticosteroid pages 1-3, sadeleer2018effectsofcorticosteroid pages 3-6)
Treatment	Exposure avoidance improved lung function in non-fibrotic HP: FVC trajectory changed from -0.24%/month to +0.92%/month (p=0.016), and DLCO from -0.23%/month to +0.37%/month with an immediate +4.0% increase (p=0.04). In fibrotic HP, FVC improved numerically to +0.28%/month but was not significant (p=0.15).	De Sadeleer et al. 2018, Journal of Clinical Medicine	Single-center cohort, exposure avoidance analysis	https://doi.org/10.3390/jcm8010014	(sadeleer2018effectsofcorticosteroid pages 6-8)
Trials	Pirfenidone trial in progressive chronic HP: adults with >10% fibrosis on HRCT and absolute FVC decline >5% in prior 6 months despite conventional therapy; randomized 1:1, n=40; endpoints included FVC and 6MWD at 6 months.	NCT04675619	Phase 2, randomized, open-label interventional trial	https://clinicaltrials.gov/study/NCT04675619	(NCT04675619 chunk 1)
Trials	Pirfenidone trial in fibrotic HP: pirfenidone 2403 mg/day vs placebo for 52 weeks; primary endpoint was change in % predicted FVC at week 52; included multidisciplinary-consensus FHP, age 18-80, FVC ≥40%, DLCO ≥30%; trial terminated during COVID-19.	NCT02958917	Phase 2, randomized, double-blind, placebo-controlled trial	https://clinicaltrials.gov/study/NCT02958917	(NCT02958917 chunk 1, NCT02958917 chunk 2)
Trials	Earlier chronic HP pirfenidone study tested pirfenidone added to prednisone + azathioprine; estimated enrollment 60; primary endpoint FVC at 26 and 52 weeks, with HRCT, 6MWD, QoL, echocardiographic PASP, and oxygen desaturation as secondary outcomes.	NCT02496182	Phase 2/3, randomized, quadruple-masked trial	https://clinicaltrials.gov/study/NCT02496182	(NCT02496182 chunk 1, NCT02496182 chunk 2)

Table: This table compiles compact, high-yield recent evidence and key comparator studies relevant to bird fancier's lung/avian hypersensitivity pneumonitis. It highlights exposure patterns, diagnostic performance, prognostic markers, treatment effects, and active/interpretable clinical trial designs for rapid knowledge-base use.

Notes on evidence limitations

Several knowledge-base fields (ICD/MeSH/MONDO/Orphanet identifiers; population prevalence/incidence; specific genetic variants; animal models) could not be populated with citable evidence using the retrieved document set.
Some retrieved items are preprints (e.g., Akkurt 2024) and should be treated as non–peer-reviewed until formally published. (akkurt2024evaluationofclinical pages 1-4)

References

(deutsch2024doesatype pages 2-4): Kamila Deutsch, Katarzyna B. Lewandowska, Agata Kowalik, Iwona Bartoszuk, Piotr Radwan-Röhrenschef, Małgorzata Sobiecka, Małgorzata Dybowska, Witold Z. Tomkowski, and Monika Szturmowicz. Does a type of inciting antigen correlate with the presence of lung fibrosis in patients with hypersensitivity pneumonitis? Journal of Clinical Medicine, 13:5074, Aug 2024. URL: https://doi.org/10.3390/jcm13175074, doi:10.3390/jcm13175074. This article has 2 citations.
(akkurt2024evaluationofclinical pages 1-4): ESMA SEVIL AKKURT, BERNA AKINCI OZYUREK, KEREM ENSARIOGLU, TUGCE SAHIN OZDEMIREL, OZLEM DUVENCI BIRBEN, HAKAN ERTURK, and TUNAHAN DOLMUS. Evaluation of clinical and radiological features of patients diagnosed with hypersensitivity pneumonia. Nov 2024. URL: https://doi.org/10.21203/rs.3.rs-5418767/v1, doi:10.21203/rs.3.rs-5418767/v1.
(okuda2024longitudinalchangesin pages 1-2): Ryo Okuda, Tamiko Takemura, Toshihiro Misumi, Akimasa Sekine, Eri Hagiwara, and Takashi Ogura. Longitudinal changes in serum immunoglobulin g testing in patients with fibrotic avian hypersensitivity pneumonitis. BMC Pulmonary Medicine, May 2024. URL: https://doi.org/10.1186/s12890-024-03063-0, doi:10.1186/s12890-024-03063-0. This article has 0 citations and is from a peer-reviewed journal.
(kypreos2022impactofnumber pages 1-2): Margaret Kypreos, Kiran Batra, Craig S. Glazer, and Traci N. Adams. Impact of number and type of identified antigen on transplant-free survival in hypersensitivity pneumonitis. PLoS ONE, 17:e0273544, Sep 2022. URL: https://doi.org/10.1371/journal.pone.0273544, doi:10.1371/journal.pone.0273544. This article has 12 citations and is from a peer-reviewed journal.
(deutsch2024doesatype pages 9-10): Kamila Deutsch, Katarzyna B. Lewandowska, Agata Kowalik, Iwona Bartoszuk, Piotr Radwan-Röhrenschef, Małgorzata Sobiecka, Małgorzata Dybowska, Witold Z. Tomkowski, and Monika Szturmowicz. Does a type of inciting antigen correlate with the presence of lung fibrosis in patients with hypersensitivity pneumonitis? Journal of Clinical Medicine, 13:5074, Aug 2024. URL: https://doi.org/10.3390/jcm13175074, doi:10.3390/jcm13175074. This article has 2 citations.
(NCT02496182 chunk 1): Pirfenidone in the Chronic Hypersensitivity Pneumonitis Treatment. Grupo Medifarma, S. A. de C. V.. 2015. ClinicalTrials.gov Identifier: NCT02496182
(sadeleer2018effectsofcorticosteroid pages 6-8): Laurens J. De Sadeleer, Frederik Hermans, Els De Dycker, Jonas Yserbyt, Johny A. Verschakelen, Eric K. Verbeken, Geert M. Verleden, and Wim A. Wuyts. Effects of corticosteroid treatment and antigen avoidance in a large hypersensitivity pneumonitis cohort: a single-centre cohort study. Journal of Clinical Medicine, 8:14, Dec 2018. URL: https://doi.org/10.3390/jcm8010014, doi:10.3390/jcm8010014. This article has 183 citations.
(sadeleer2018effectsofcorticosteroid pages 1-3): Laurens J. De Sadeleer, Frederik Hermans, Els De Dycker, Jonas Yserbyt, Johny A. Verschakelen, Eric K. Verbeken, Geert M. Verleden, and Wim A. Wuyts. Effects of corticosteroid treatment and antigen avoidance in a large hypersensitivity pneumonitis cohort: a single-centre cohort study. Journal of Clinical Medicine, 8:14, Dec 2018. URL: https://doi.org/10.3390/jcm8010014, doi:10.3390/jcm8010014. This article has 183 citations.
(sadeleer2018effectsofcorticosteroid pages 3-6): Laurens J. De Sadeleer, Frederik Hermans, Els De Dycker, Jonas Yserbyt, Johny A. Verschakelen, Eric K. Verbeken, Geert M. Verleden, and Wim A. Wuyts. Effects of corticosteroid treatment and antigen avoidance in a large hypersensitivity pneumonitis cohort: a single-centre cohort study. Journal of Clinical Medicine, 8:14, Dec 2018. URL: https://doi.org/10.3390/jcm8010014, doi:10.3390/jcm8010014. This article has 183 citations.
(intra2024theroleof pages 1-2): Jari Intra, Alice Biffi, Francesca Basta, Cristina Delfini, Nicoletta Novati, Elisa Zucchetti, Fabrizio Luppi, and Marco Casati. The role of serum igg precipitins against six typical organic antigens involved in hypersensitivity pneumonitis: a 10-year retrospective study of a referral interstitial lung disease centre. International Journal of Translational Medicine, 4:381-386, Jun 2024. URL: https://doi.org/10.3390/ijtm4020025, doi:10.3390/ijtm4020025. This article has 5 citations.
(intra2024theroleof pages 5-6): Jari Intra, Alice Biffi, Francesca Basta, Cristina Delfini, Nicoletta Novati, Elisa Zucchetti, Fabrizio Luppi, and Marco Casati. The role of serum igg precipitins against six typical organic antigens involved in hypersensitivity pneumonitis: a 10-year retrospective study of a referral interstitial lung disease centre. International Journal of Translational Medicine, 4:381-386, Jun 2024. URL: https://doi.org/10.3390/ijtm4020025, doi:10.3390/ijtm4020025. This article has 5 citations.
(okuda2024longitudinalchangesin pages 7-8): Ryo Okuda, Tamiko Takemura, Toshihiro Misumi, Akimasa Sekine, Eri Hagiwara, and Takashi Ogura. Longitudinal changes in serum immunoglobulin g testing in patients with fibrotic avian hypersensitivity pneumonitis. BMC Pulmonary Medicine, May 2024. URL: https://doi.org/10.1186/s12890-024-03063-0, doi:10.1186/s12890-024-03063-0. This article has 0 citations and is from a peer-reviewed journal.
(akkurt2025fibroticpatternsand pages 12-12): Esma Sevil Akkurt, Berna Akıncı Ozyurek, Kerem Ensarioglu, Tugce Sahin Ozdemirel, Ozlem Duvenci Birben, Hakan Erturk, and Tunahan Dolmus. Fibrotic patterns and diagnostic correlates in hypersensitivity pneumonitis: clinical, radiologic, and hematologic insights. Diagnostics, 15:3137, Dec 2025. URL: https://doi.org/10.3390/diagnostics15243137, doi:10.3390/diagnostics15243137. This article has 0 citations.
(okuda2024longitudinalchangesin pages 2-4): Ryo Okuda, Tamiko Takemura, Toshihiro Misumi, Akimasa Sekine, Eri Hagiwara, and Takashi Ogura. Longitudinal changes in serum immunoglobulin g testing in patients with fibrotic avian hypersensitivity pneumonitis. BMC Pulmonary Medicine, May 2024. URL: https://doi.org/10.1186/s12890-024-03063-0, doi:10.1186/s12890-024-03063-0. This article has 0 citations and is from a peer-reviewed journal.
(kypreos2022impactofnumber pages 4-5): Margaret Kypreos, Kiran Batra, Craig S. Glazer, and Traci N. Adams. Impact of number and type of identified antigen on transplant-free survival in hypersensitivity pneumonitis. PLoS ONE, 17:e0273544, Sep 2022. URL: https://doi.org/10.1371/journal.pone.0273544, doi:10.1371/journal.pone.0273544. This article has 12 citations and is from a peer-reviewed journal.
(kypreos2022impactofnumber pages 5-7): Margaret Kypreos, Kiran Batra, Craig S. Glazer, and Traci N. Adams. Impact of number and type of identified antigen on transplant-free survival in hypersensitivity pneumonitis. PLoS ONE, 17:e0273544, Sep 2022. URL: https://doi.org/10.1371/journal.pone.0273544, doi:10.1371/journal.pone.0273544. This article has 12 citations and is from a peer-reviewed journal.
(NCT02958917 chunk 1): Evans Fernandez Perez. Study of Efficacy and Safety of Pirfenidone in Patients With Fibrotic Hypersensitivity Pneumonitis. Evans Fernandez Perez. 2017. ClinicalTrials.gov Identifier: NCT02958917
(NCT02958917 chunk 2): Evans Fernandez Perez. Study of Efficacy and Safety of Pirfenidone in Patients With Fibrotic Hypersensitivity Pneumonitis. Evans Fernandez Perez. 2017. ClinicalTrials.gov Identifier: NCT02958917
(NCT04675619 chunk 1): Eman Shebl. Evaluation of the Efficacy of Pirfenidone in Progressive Chronic Hypersensitivity Pneumonitis. Zagazig University. 2019. ClinicalTrials.gov Identifier: NCT04675619
(intra2024theroleof pages 4-5): Jari Intra, Alice Biffi, Francesca Basta, Cristina Delfini, Nicoletta Novati, Elisa Zucchetti, Fabrizio Luppi, and Marco Casati. The role of serum igg precipitins against six typical organic antigens involved in hypersensitivity pneumonitis: a 10-year retrospective study of a referral interstitial lung disease centre. International Journal of Translational Medicine, 4:381-386, Jun 2024. URL: https://doi.org/10.3390/ijtm4020025, doi:10.3390/ijtm4020025. This article has 5 citations.
(NCT02496182 chunk 2): Pirfenidone in the Chronic Hypersensitivity Pneumonitis Treatment. Grupo Medifarma, S. A. de C. V.. 2015. ClinicalTrials.gov Identifier: NCT02496182

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Subtypes

Pathophysiology

Histopathology

Pathograph

Phenotypes

Genetic Associations

Medical Actions

Environmental Factors

Biochemical Markers

Differential Diagnoses

Related Datasets

Clinical Trials

Source YAML

References & Deep Research

References

Deep Research

Bird Fancier’s Lung (BFL) / Avian Hypersensitivity Pneumonitis (HP): Disease Characteristics Research Report

Executive summary (current understanding)

1. Disease information

1.1 Overview/definition

1.2 Key identifiers (ICD/MeSH/MONDO/Orphanet)

1.3 Synonyms / alternative names

1.4 Evidence sources

2. Etiology

2.1 Disease causal factors

2.2 Risk factors

Environmental/occupational risk factors

Genetic susceptibility (host factors)

2.3 Protective factors

2.4 Gene–environment interactions

3. Phenotypes (clinical presentation)

3.1 Core clinical phenotypes (with suggested HPO terms)

3.2 Phenotype characteristics: fibrotic vs non-fibrotic

3.3 Frequency and real-world distributions from recent studies

3.4 Quality of life (QoL) impact

4. Genetic / molecular information

4.1 Causal genes

4.2 Biomarkers and molecular tests (2023–2024 emphasis)

Antigen-specific IgG (“precipitins”)

5. Environmental information

5.1 Environmental determinants and exposure sources

5.2 Lifestyle factors

5.3 Infectious agents

6. Mechanism / pathophysiology

6.1 Current mechanistic model (causal chain)

6.2 Immune system involvement and key processes (ontology suggestions)

6.3 Recent mechanistic/biomarker angle: exposure persistence and serology

7. Anatomical structures affected

7.1 Organ and tissue level (UBERON suggestions)

8. Temporal development

8.1 Onset and course

9. Inheritance and population

9.1 Epidemiology

9.2 Population demographics and distributions (from available cohorts)

10. Diagnostics

10.1 Key diagnostic concepts (current practice)

10.2 Recent diagnostic data points

10.3 Differential diagnosis

11. Outcome / prognosis

11.1 Prognostic strata: fibrotic vs non-fibrotic

11.2 Antigen identification and outcomes (real-world prognostic implications)

12. Treatment

12.1 Core management principle: exposure remediation/avoidance

12.2 Corticosteroids and immunosuppression

12.3 Antifibrotics and clinical trials (real-world implementation and ongoing evidence)

13. Prevention

14. Other species / natural disease

15. Model organisms

Recent developments (2023–2024) highlighted

Structured evidence table

Notes on evidence limitations