tash spellFollow

I keep getting hit with this "tash"-something spell in LDoN. It reduces my fire and cold resists, and I cannot seem to get it dispelled with either remove poison or disease. Help.

I konw about the standard tasiania spells which chanters cast which lower one's magic resist. IIRC they are cured with cure poison. I checked out my magic resist and it was not horrible, but my fire and cold resists (normally pretty high maybe 60's to 80's not sure) were both negative. After a short time I rechecked and they were still aweful but maybe each was about 10 points higher. (Sorry I can't recall exact name - I did search alla's for all spells beginning with "tash" and I couldn't find anything with fire/cold resist decreases.)

General question: how can you tell if cure poison is working? Will it give me (the one being cured) or the cleric a different message if it is working than if it is not?

Any help welcome.

(I'm level 58 and my group level average was probabaly in the 55-56 range. We were on a EC mission, but I think I got the same nasty spell from an Everfrost mission, too).