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7 out of 7

Byssinosis occur due to? (LQ)

A Cotton fiber

B Sugarcane

C Aspergillus clavatus

D Proteins in bird droppings

Ans. A

Cotton fiber

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.

Tests Acute:

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.