Indeed. If you are casting purge to remove curses, poisons, or both at the same time; they are removed but the icons for these negatives spells will remain their duration. I am not sure why, though I can tell you with 99.8% certainty that casting purge does what it is supposed to as of this post.
--Sturger--
P.S. --FYI-- nothing is 100% certain... IMO!