My mom and dad owned a summer home in the country. After my dad got sick and passed, it sat empty for nearly a year. When we went to clear it out to sell it, it was full of mold (like, growing on the walls like something out of a horror movie) and mouse crap (in and on every surface). You can imagine the things I worried about!
But nothing happened. I was elbow-deep in mouse refuse for a week. And I was fine. (Thoroughly disgusted and annoyed, but fine.)