Hypersensitivity Pneumonitis Types Causes Symptoms Treatment


Hypersensitivity Pneumonitis

Hypersensitivity pneumonitis (HP) is an inflammation of the lung caused by the body’s immune reaction to airborne particles.

Types of Hypersensitivity Pneumonitis

  • Acute Hypersensitivity Pneumonitis: Occurs 4-12 hours after heavy exposure to particles.
  • Chronic (long-term) hypersensitivity pneumonitis: Causes lung scarring (fibrosis).

What are examples of hypersensitivity pneumonitis?

Examples include:

  • Farmer’s lung disease: Exposure to mold spores in hay.
  • Pigeon breeder’s disease: Exposure to protein particles in pigeon droppings.
  • Sauna takers’ disease: Exposure to mold growing in wet containers.
  • Mushroom workers’ disease: Exposure to moldy compost.
  • Bagassosis: Exposure to moldy sugar cane.
  • Winemaker’s lung: Exposure to a fungus on grapes called Botrytis cinerea.
  • A rare case of hypersensitivity to Canadian goose droppings.

A table lists the types of compounds, bacteria, and molds known to cause hypersensitivity pneumonitis.

Disease Name Antigens Exposure Bagassosis

Mushroom worker lung

Metalworking fluids HP

Hot tub HP

Lifeguard’s lung

Farmer’s lung

Humidifier lung

Compost HP

Malt worker lung

Peat moss HP


Maple bark HP

Wood pulp worker lung

Wood trimmer lung

Tree cutter lung

Dry rot HP


Japanese summer-type HP

Cheese washer lung

Tobacco worker lung

Greenhouse HP

Esparto grass HP

Soy sauce brewer’s lung

Bird breeder lung

Mollusc shell HP

Animal handler lung

Wheat weevil HP

Silk production HP

Isocyanate HP


Bacteria (Thermophilic actinomycetes) Moldy bagasse (pressed sugarcane)
Bacteria (Thermophilic actinomycetes) Mushroom compost
Bacteria (Mycobacterium immunogenum) Mist from metalworking fluids
Bacteria (Mycobacterium avium complex) Mist from hot tubs
Bacteria (Endotoxin) Indoor swimming pool
Bacteria (Thermophilic actinomycetes)
Fungus (Aspergillus species)
Moldy hay
Bacteria (T. candidus, Bacillus subtilis, B. cereus, Klebsiella oxytoca)
Fungus (Aureobasidium pullulans)
Amoebae (Naegleria gruberi, Acanthamoeba polyhaga, Acanthamoeba castellani)
Mist from standing water
Fungus (Aspergillus) Compost
Fungus (Aspergillus clavatus) Moldy barley
Fungi (Monocillium sp, Penicillium citreonigrum) Peat moss
Fungus (Penicillum frequentans) Moldy cork dust
Fungus (Cryptostroma corticale) Moldy wood bark
Fungus (Alternaria species) Moldy wood pulp
Fungus (Rhizopus species) Moldy wood trimmings
Fungi (Penicillium (three species), Paecilomyces sp.,
Aspergillus niger, Aspergillus sp., Rhizopus sp.)
Wood chips from living maple and oak trees
Fungus (Merulius lacrymans) Moldy rotten wood
Fungi (Graphium species, Pullularia species) Moldy wood dust
Fungus (Trichosporon cutaneum) Damp wood and mats
Fungus (Pencillum casei or P.roqueforti) Cheese casings
Fungus (Aspergillus sp.) Moldy tobacco
Fungi (Aspergillus sp., Penicillium sp., Cryptostroma corticale) Moldy soil
Fungus (Aspergillus fumigatus) Moldy esparto is used to produce ropes, canvas, sandals, mats, baskets, and paper paste
Fungus (Aspergillus oryzae) Fermentation starter for soy sauce
Avian proteins Bird droppings and feathers
Aquatic animal proteins Mollusc shell dust
Animal proteins urine, serum, fur
Wheat weevil (Sitophilus granarius) Infested flour
Silkworm larvae proteins Silkworm larvae
TDI, HDI, MDI Paints, resins, polyurethane foams
Trimellitic anhydride Plastics, resins, paints
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What triggers hypersensitivity pneumonitis?

Particles that trigger hypersensitivity pneumonitis include bacteria, mold, fungi, or inorganic matter.

What are the symptoms of hypersensitivity pneumonitis?

Acute Hypersensitivity Pneumonitis

Symptoms include:

  • Fever
  • Chills
  • Coughing
  • Shortness of breath
  • Body aches, malaise

Chest X-ray may show small nodules in the lungs. Symptoms usually subside hours to days after exposure. Medical evaluation is necessary to determine treatment.

Chronic Hypersensitivity Pneumonitis

Symptoms include:

Chronic disease occurs after prolonged low-grade exposure to offending particles.


How is hypersensitivity pneumonitis diagnosed?

Many cases are unrecognized. History of repeated episodes of symptoms after exposure is important. Chest X-ray and high-resolution CT scan are used for diagnosis. Lung function tests are performed. Blood antibody and skin tests may be inconclusive. Biopsy may be necessary. Exposure history is crucial for accurate diagnosis.

What is the treatment for hypersensitivity pneumonitis?

Avoiding repeated exposures to the offending particles is crucial. Early diagnosis and prevention lead to a good prognosis.

What are complications of hypersensitivity pneumonitis?

Prolonged exposures can cause permanent lung damage and scarring.


Rose, CS, Lara AR. Hypersenstivity pneumonia In: Mason RJ, Broadus VC, Martin TR, et al. Eds. Murray and Nadel’s Textbook of Respiratory Medicine. 5th ed. Philadelphia, Pa; Saunders Elsevier; 2010; Chap 66.

Saltoun, et. al. Hypersensitivity pneyonitis resulting from community exposure to Cadada goose droppings when an exteran environmental antigen becomes an indoor environmental antigen. Annals of Allergy, Asthma and Immunology. Vol 84 Issue 1; Pgs 84-86 January 2000.

Takahashi, et. al. Serum Kl-6 Concentrations in Dairy Farmers. Chest. August 2000, vol. 118 no. 2 445-450.

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