This is my main problem, too (pinworms, or roundworms) and my most nagging symptom is anal itching.
At this point, diet and herbs have reduced the itching much, but here is some even better advice:
Each morning and night I use tea tree oil topically down there--although I mix it first with olive oil as it is just to harsh to apply straight (I just get some olive oil on a cotton ball and then add a touch of tea tree).
The best results I have had so far have been from soaking my entire body in an Epsom Salt bath--once I used 3-4 cups in the tub (although this may be strong for a beginner) and it actually made me sweat--stayed in for 45 minutes and NO symptoms that night.
I have also been trying with warm water and garlic enemas (boil the garlic for 10 minutes, then let cool until lukewarm)--this has also proved effective in itching relief.
with pinworms, it's also really important to be sure that you don't recontaminate yourself, which i think has been part of my problem from the beginning--always wear underwear, wash your bedding regularly, and was your hands well, especially if you are ever itching. recently i went to an acupunturist and she advised that i iron my underwear after washing, for good measure.
on top of all this, of couse reducing candida and the "damp" environment that harbors the parasites will enable you to kick them for good.
ok, just wanted to chime in and add some recommendations, as i've just been thinking so much about this lately!!