Bookwyrm627: There are lots of possible sources. Where are you in the game? What have you been doing recently? How long has it been since you noticed the debuff?
InfamousGeezer: I have been doing the beggers nest but needed to go back and upgrade equipment etc. I discovered that after using the stone that returns you to the temple. The main quest giver Aribeth heals those annoying debuffs. I found out one way to remove them by luck.
I seem to recall that most acts have a healer that will restore you to full hp and remove bad statuses when asked.
I don't remember what could cause strength damage/drain in the beggar's nest. Might have been a negative energy trap? Attacks by Shadows do strength damage, but it comes back after time passes (I don't remember if just resting is sufficient). I think disease might cause stat damage, but resting should eventually let you make enough Fort saves to take care of it. Any strength drain spells should have worn off after a while.