If you want to lose the solace that fact has provided you, here’s another possibly also false but no less comforting bit of trivia:
spoilerLeeches after feeding would love nothing more than a dark, somewhat moist, somewhat warm, somewhat tight environment. Which a human has and is probably something you don’t want a leech to get anywhere near, be glad there’s no such thing as a Analwig. Oh and land leeches exist.