Hypersensitivity Pneumonitis: Common Features


  • Symptoms: presents acutely, as flu-like illness with cough; subacutely, as recurrent "pneumonia"; and chronically, as exertional dyspnea, productive cough and weight loss;

    Signs: abnormal chest x-ray in most patients; crepitant rales in some cases; specific precipitating antibodies in some cases; pulmonary function tests show a restrictive defect in early disease and a restrictive, obstructive or mixed defect in late disease;

    Latency: few weeks to years;

    Onset of symptoms after exposure: 4 to 12 hours;

    Repeated exposure to: 1) bioaerosols of microbial or animal antigens; or 2) a few reactive chemicals;

    Resolution: improvement or complete recovery if exposure terminated early; otherwise, may progress to interstitial fibrosis;

    Comments: In the acute form, symptoms may resolve within a few days following the exposure.

Note: A bioaerosol is a suspension of particles of biologic origin in a gas; it can be a mist or a dust.


Some of the Types, Antigens and Exposures that Have Been Identified




Farmer's lung Thermophilic actinomycetes
Fungus (Aspergillus species)
Moldy hay
Bagassosis Thermophilic actinomycetes Moldy bagasse (pressed sugarcane)
Malt worker's lung Fungus (Aspergillus clavatus) Moldy barley
Humidifier lung Bacteria (T. candidus, Bacillus subtilis, B.   cereus, Klebsiella oxytoca)
Fungus (Aureobasidium pullulans )
Amoebae (Naegleria gruberi, Acanthamoeba polyhaga, Acanthamoeba castellani)
Mists from standing water
Mushroom worker's lung Thermophilic actinomycetes Mushroom compost
Compost lung Fungus (Aspergillus) Compost
Suberosis Fungus (Penicillum frequentans) Moldy cork dust
Maple bark-stripper's lung Fungus (Cryptostroma corticale) Moldy wood bark
Wood pulp worker's lung Fungus (Alternaria species) Moldy wood pulp
Wood trimmer's disease Fungus (Rhizopus species) Moldy wood trimmings
Sequoiosis Fungi (Graphium species, Pullularia species) Moldy wood dust
Japanese summer-type HP Fungus (Trichosporon cutaneum) Damp wood and mats
Cheese-washer's lung Fungus (Pencillum casei or P.roqueforti) Cheese casings
Metalworking fluids HP Mycobacteria chelonae; fungi Microbially contaminated, water-based MWFs
Bird-breeder's lung Avian proteins Bird droppings and feathers
Mollusc shell HP Aquatic animal proteins Mollusc shell dust
Isocyanate HP TDI, HDI, MDI Paints, resins, polyurethane foams
TMA HP Trimellitic anhydride Plastics, resins, paints

References: "Hypersensitivity Pneumonitis" by Cecile Rose in (Harber), "Hypersensitivity Pneumonitis" by Yvon Cormier in (Rom), "Occupational Lung Diseases" by John Balmes and Cornelius Scannell in (LaDou), and Occupational Exposure to Metalworking Fluids, NIOSH, (http://www.cdc.gov/niosh/metalw.html).

  Revised August 05, 2005