Answer:
a fungal infection
Explanation:
Spores are what spread and create new fungus, spores are single unit reproductive cells of non flowering plants, fungi and algae, from the hiking in the woods and breathing in the spores if his organism and immune system is weak he could develop a fungal infection if the fungus grow inside of his organism, mostly in his lungs giving that it is a humid, dark environment with great amount of oxygen.
