Can you get any diseases from putting hands in a fish tank?

Stupid question....can you get diseases from putting your hands in a fish tank (like when your cleaning or moving ornaments around...etc) My tanks DON'T have filters, they are 5 gal. and hold betta's (which aren't big fans of alot of current or water movement) and I frankly didn't want to hle with filters anyway. I change the water every few days. I've been using gloves when I clean the tank...but that gets to be a pain after awhile. I've seen lots of people stick their hands right into a tank...so guessing it's ok???