Is the effect of a curse in TES Arena permanent?

Once a curse is lifted, its effects are gone.

From the game's manual:

A curse is similar to a disease except that it affects your INT, WIL, PER, and LUC. As with all other degenerative attacks, if any of your stats reach zero, you will die. The good thing about curses is that they seldom have a duration long enough to threaten your life. Still, having your INT down to 15 isn’t helpful, nor is it safe. If you are hit with another curse it could kill you. Follow the steps you would if inflicted with a disease and you should be able to ward off a curse or banish it at a temple.

^Source