Spells: Tash Un-Curable

[Drytan]

I have always known Tash to be a disease based spell-line that is curable. I fought an enchanter last night, roughly level 44. After 4 doses of my Counteract Disease Pot, Tashani did not get cured. As I remember it, it wasn't only curable, but very easily at that... 1 dose even past level 70.