There is also exposure from a respiratory fungal infection called histoplasmosis. Dust from untreated feathers from birds that have been raised in a confined area, particularly poultry such as turkeys or chickens, can transmit this fungus to humans. Most of the time it only causes symptoms associated with the flu or pneumonia, but it also can cause serious heath problems it gets into your bloodstream. Fortunately, it is treatable with drugs, but trust me you don't want to go down this road.
Stringstretcher, I truly am sorry to hear about your health problems and I can only hope that everyone on this forum will act on your advise.