I never gave it much thought. Are the eggs big enough to see? My understanding is that pinworm eggs float in the air and we breath them in. There is no way to avoid this without wearing a mask. Apparently ascaris eggs are just about as common.
I once read where Hulda Clark left a cup of water sitting on the table over night. When she checked it the next day, she found an ascaris egg floating in it. Seems to me recontamination is inevitable, given the ubiquitous nature of parasites. Washing hands often and routine maintenance is my only plan for salvation... redemption.... liberation... whatevers-