What causes bird-keepers lung?

Answer 1

You are probably referring to a condition known as "bird fancier's lung". Which is often miswritten as "bird keeper's lung".

Bird fancier's lung is a form of hypersensitivity pneumonitis, a medical condition in which the lungs become inflamed with granuloma formation.
It is caused by over-exposure to avian proteins found in the dust of bird droppings (and sometimes the feathers of certain species).


Further reading:

• Bird Fancier's Lung on Wikipedia

Answer 2

Bird-keepers lung, also known as hypersensitivity pneumonitis, is caused by inhaling organic dust from bird feathers, droppings, or dander. This dust triggers an immune response in the lungs, leading to inflammation and symptoms such as cough, shortness of breath, and chest tightness. The condition is more common in individuals who are regularly exposed to birds in their home or work environment.

Answer 3

Partially or entirely inhaling a bird repeatedly.