Extrinsic Allergic Pneumonia, also known as Allergic Interstitial Pneumonitis, Hypersensitivity Pneumonitis, is a kind of inflammatory syndrome, more specifically, a lung disorder. Breakdown of the nameExtrinsic: origin is an outside matter – antigen.
Allergic: An allergic reaction from the antigen is the cause.
Pneumonia: inflammation within the lungs.
There are variations in the syndrome depending upon the antigen and the amount of exposure. The exposure of antigen can be domestic or industrial depending on the environment. The cause of Extrinsic allergic pneumonia is the continuous inhalation of antigens like dust, bacteria, chemicals, bird feathers or droppings, bioaerosol, etc. These antigens induce an allergic reaction and thus result in inflammation within the lungs (pneumonitis) in alveoli and small airways (bronchioles). Types of Extrinsic allergic pneumonia:
Extrinsic allergic pneumonia differentiates based on the kinds of antigens provoking the syndrome. There are around 200 antigens observed till date, some of them are discussed below. The most common types of Extrinsic allergic pneumonia are Bird Fancier’s Lung and Farmer’s lung.
1. Bird fancier's lung, bird breeder's lung, pigeon breeder's lung, and poultry worker's lung have Avian proteins as antigen. It results from exposure to feathers and bird droppings.
2. Chemical worker's lung–Isocyanate HP has Toluene Diisocyanate (TDI), Hexamethylene Diisocyanate (HDI), or Methylene bisphenyl isocyanate (MDI) as Antigens. This results from exposure to paints, resins, and polyurethane foams.
3. Coffee worker's lung has coffee bean protein as antigen. A person suffers from it upon prolonged exposure to coffee bean dust.
4. Compost Lung has Aspergillus as an allergen and is caused due to exposure to compost.
5. Detergent worker's disease, as the name suggests, emerges due to detergent exposure. Bacillus subtilis enzymes are the antigen.
6. Farmer's lung has two antigens moulds - Aspergillus species and bacteria - Thermophilic actinomycetes, Thermoactinomyces vulgaris, Saccharopolyspora Rectivirgula, Absidia Corymbifera, Eurotium Amstelodami. Farmers are at high risk when exposed to moldy hay.
7. Japanese summer house HP or Japanese summer-type HP results from continuous exposure to damp wood and Japanese mats called Tamai. The antigen's name is Trichosporon Cutaneum.
8. Laboratory workers' lung develops due to laboratory rats where male rat urine protein acts as an antigen for the body.
9. In Miller's lung, Sitophilus Granarius (wheat weevil) is the antigen, which enters the body when the person is under the exposure of dust-contaminated grain.
10. For Tap water HP, the antigen is yet unknown but results from exposure to contaminated tap water