I'm currently in Vietnam and my potty trained 3 yr old daughter is sitting on the seats here without carefully constructed TP barriers. I can assure you that toilets are worse here than whatever you're dealing with.

TP and those silly seat covers are too thin to protect against anything, and unless the back of your legs and butt are covered in open sores, you will be fine regardless. It's why God gave us skin--keeps the bad stuff out.

Seriously though, it's so dirty here and my boy--17 months--WILL NOT STOP putting things in his mouth that he finds, or just touching the ground and then his mouth/face, or whatever. It's horrific. Today was the best when he idly ran his hands through some mucous that someone hacked up on the steps of a roadside rest area (like a Vietnamese truck stop). It's good no one around me spoke English due to the curses I let slip out while I frantically searched for a napkin to wipe his hands. If he survives I'm writing hand sanitizer companies a bunch of lovely thank you notes.