THIS ONE IS ACTUALLY CORRECT - THE PROPER TERM IS CANDIDA. It can be eliminated through diet alterations. I heard this from a friend who is very knowledgeable about diets, proper food - so I trust her.
Another condition an itchy anus can indicate, or so I've read, is gall bladder problems.
I lean more toward the candida.
Good luck - I admire you bringing this health topic onto this forum - obviously you were legitimately looking for help/answer. Disregard are the 'tards with their supposedly funny comments and good luck!