16th January 2024

Aetiology

There are a vast range of implicated antigens in HP. The most common include the following:

Bacteria/Fungi

• Thermophilic actinomycetes-this includes Micropolyspora faeni and Thermoactinomyces vulgaris
• • Farmer’s lung
    • Occurs following exposure to mouldy crop
    • Micropolyspora faeni is the most common antigen
• Mycobacterium avium complex (MAC)- Found in poorly maintained hot tubs
• Aspergillus clavatus– malt worker’s lung (found in mouldy malt)
• Penicillium casei– cheese-worker’s lung (found in mouldy cheese)

Animal proteins

• Avian proteins– Bird fancier’s lung
  • Found in bird droppings or feathers of birds
  • Includes pigeons, chickens, turkeys, parakeets, and ducks 

Reactive chemicals

• Acid anhydrides 
• Isocyanates- these include varnishes and chemical foams
• Metalworking fluids

In addition, colonisation of various atypical mycobacteria and moulds in wind instruments can be implicated in the development of HP amongst wind instrument players.