Let's put it this way. When I first moved to Hawaii, a place that has less humidity than southern Florida, I threw a leather belt in the top of my closet. One month later I took it out and it was completely green. Granted Hilo got a lot of rain, but it shows mold is no joke. I was constantly worried about fungus there. Now, even though we live in the desert, I keep my leather cases in one drawer and the cameras for them in another. Don't forget that a camera that gets fungus into it's lens can give it to another camera you have. Spores are microscopic and seem to thrive in lenses, munching away at the coatings.