I run into this from time to time. You would think that badass bugs were pathogens, but it turns out that most pathogens are wimpy. At least, in terms of their ability to tolerate uncomfortable conditions. They are so well-evolved to take advantage of our warm, wet, nutritious bodies that they tend to have a tough time living an alternate lifestyle. Some of them do go into a dormant state, so they're pretty hardy that way, but they aren't generally thriving.