Can affect any farmer who works with wet hay or other moldy dust. Small farmers who have to directly thresh and handle their hay are most at risk, as are those living in cold and humid areas where damp weather is common. Pigeon breeder's lung. A substance has been found in pigeon droppings that may cause the allergic reaction, but there may be more than one such substance. Besides pigeons, the disorder may follow exposure to ducks, geese, pheasants, and even canaries.
Parakeets produce an especially severe form of disease.
Most patients are middle-aged women, who usually care for birds either at home or on bird breeding farms. Caused by bagasse, a substance produced when juice is extracted from sugar cane and is used in making paper and explosives. A fungus is probably responsible. Young and middle-aged men who work in the sugar industry are at risk. A similar condition affecting workers who inhale dust from cotton, flax, or hemp.