History and exam
Key diagnostic factors
common
exposure to avian protein antigen, especially excrement
Exposure to birds and cleaning cages may cause acute symptoms.
Where onset of symptoms is insidious, the timing of exposure is often missed and the pulmonary fibrosis may be dismissed as idiopathic.
mould in work environment
Exposure to mouldy air conditioners, humidifiers, or ventilation systems, or to organic products that are mouldy such as hay, grain, wood, wood dust, or sugar cane, may precipitate acute symptoms 6 to 18 hours later.
occupational exposure to chemicals
dyspnoea
Almost always present; where symptoms present acutely, it is typically episodic, associated with fevers, cough, and malaise.
May be insidious.
cough
Cough is almost always present; where symptoms present acutely, it may be episodic and associated with fevers, dyspnoea, and malaise.
May be insidious.
Other diagnostic factors
common
fever/chills
More common with acute presentations of HP and non-fibrotic disease.
Fever is usually low grade.
malaise
Where symptoms present acutely, it is typically episodic, associated with fevers, cough, and dyspnoea.
May be insidious.
weight loss/anorexia
Weight loss and anorexia are common with advanced disease.
bibasilar rales
Typically present during acute symptomatic episodes of HP but not present between episodes.
Bibasilar or diffuse rales are usually present in patients with ongoing disease.
diffuse rales
Bibasilar or diffuse rales are usually present in patients with ongoing disease.
clubbing
Approximately 50% of patients with advanced disease will have clubbing.
Risk factors
weak
smoking
Reduces B7 co-stimulatory molecules on macrophages, thereby reducing the macrophage contribution to the inflammation.
viral infection
Increases B7 co-stimulatory molecules on macrophages, thereby increasing the macrophage contribution to the inflammation.
exposure to avian protein antigen
High levels of exposure to antigen are typically needed.
Associated with pigeon breeder's lung, bird fancier's lung, and budgerigar fancier's disease.
exposure to mould antigen
Including Aspergillus, Alternaria, Penicillium, and Trichosporum.
High levels of exposure to antigen are typically needed.
exposure to bacterial antigen
Including thermophilic Actinomycetes, Bacillus, Pseudomonas, Acinetobacter, and Klebsiella.
exposure to diisocyanate (e.g., epoxy resin)
High levels of exposure to antigen are typically needed.
exposure to acid anhydride antigen (e.g., paint refinisher)
High levels of exposure to antigen are typically needed.
exposure to metalworking fluid
Reported to account for about one-half of all cases of occupational HP in the UK.[18]
nitrofurantoin, methotrexate, roxithromycin, and rituximab
May cause drug-induced HP.[19]
e-cigarettes
Case reports indicate a possible association between the use of electronic nicotine delivery systems (vaping) and HP.[22]
sertraline
One case report describes the clinical presentation of HP associated with sertraline.[23]
ayurvedic medicine
HP has been reported in a person who consumed ayurvedic medicine.[20]
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