Pinworms are not common. In my career as a nurse I never saw or treated a case of it. I never had a patient complain of rectal itching. Pinworms are also easier to get rid of than you think.
large bottle of Vaseline (generic ok)
Baby wipes (generic ok)
plastic sandwich bags (non zipper type, cheaper the better)
Each time the toilet is used:
Cleanse first with toilet paper
Then cleanse the rectum with a baby wipe
Repeat until the baby wipe is clear of feces
Place a plastic bag over your hand
Scoop up about a teaspoon of Vaseline
Apply it to rectum in generous amounts
DO not put your bare hand in the vaseline jar as this will make it dirty.
Do this for at least one month. The adult worms will be unable to lay eggs in the Vaseline and the colony will die. Do not use garlic or anything else as this will irritate the skin.
Shower daily and change underwear frequently.
Hang sheets in the sun as often as possible.
Pinworms are not terribly contagious. If the eggs could survive on toilet seats everyone would have them. So relax and just declare war on the little buggers.