Slow you down, make you weaker, maybe even the more deadly ones would kill you. Your vision would be blurred, your movement slowed, your attacks weaker, your stamina lowering... you attempt to escape back to civilization before you completely succumb to the disease. Maybe a bit too harsh, but it would be more realistic!
Just like Daggerfall.
I like it.
However, without attributes, how would a disease go about making you slower and weaker?
Strength and speed no longer exist and no matter what the 'im glad attributes are gone' crowd insists, absolutely not everything they did is still in the game.