Byssinosis occur due to? (LQ)
|D||Proteins in bird droppings|
Extrinsic allergic alveolitis (EAA)
1). In sensitized individuals, inhalation of allergens (fungal spores or avian proteins provokes a hypersensitivity reaction. In the acute phase, the alveoli are infiltrated with acute inflammatory cells.
2). With chronic exposure, granuloma formation and obliterative bronchiolitis occur. There is involvement of type 3 hypersensitivity, (not type 1).
1). Bird fancier's Q and pigeon fancier's lung (proteins in bird droppings).
2). Farmer's Q and mushroom worker's lung (Micropolyspora faeni, Thermoactinomyces vulgaris).
3). Malt worker's Q lung (Aspergillus clavatus).
4). Bagassosis Q (Thermoactinomyces). Occur in sugarcane workers.
5). Byssinosis = cotton fiber
Clinical features 4-6h post-exposure: Fever, rigors, myalgia, dry cough, dyspnea, crackles (no wheeze).
3). Chronic: Weight loss, exertional dyspnea, Type I respiratory failure, cor pulmonale.
4). CXR: mid-zone mottling/consolidation.
5). Lung function tests: reversible restrictive defect Q; reduced gas transfer Q during acute attacks.
In Chronic exposure:
1). Blood tests: positive serum precipitins.
2). CXR: upper-zone fibrosis; honeycomb lung.
3). Lung function tests: persistent changes as above.
4). Bronchoalveolar lavage (BAL) fluid shows t lymphocytes and mast cells
1). Acute attack: Remove allergen and give O2 (35-60%), then Oral prednisolone (40mg/24h pO), followed by reducing dose.
2). Chronic: Avoid exposure to allergens, or wear a face mask or +ve pressure helmet. Long-term steroids often achieve CXR and physiological improvement.