They all showed the same symptoms and it was not unreasonable at the time to consider them all manifestations of the same thing.
The converse may also occur.
Prior to discovery of the link between staphylococcus bacteria and the various diseases it can produce, medical practitioners referred to those manifestations as if they were unique and separate diseases: "The Itch." "The Rash." "The Fever." "The Pustules." "Septicemia." "Rheumatic Fever," etc. Now we simply say,
If you understand mildew and mold to be general terms for fungus:
You're darn tootin' they can!
Ever hear of Athlete's Foot? Ringworm? Jock itch? Yeast infection?
Inhalation of certain mold spores can cause respiratory difficulty, hallucinations, even death; especially among infants, the elderly, and those with lung disease.