I think we are forgetting that not all parasites are visible to the eye. The microscopic kind are even more dangerous, now imagine some guy in a lab getting $15/hour going through human crap looking for eggs all day....I don't think they enjoy their job enough to give a 2nd look. How the hell would you distinguish one parasite egg from another? I passed some parasites with a SWC, and sent them to the dr to get tested...results negative!!! Like they always are. These were parasites, they were not food particles! We all have parasites, it's a matter of how our immune system handles them. Some have no symptoms, some fall apart. I wish there was an easy test, I personally finally found a lab that picked something, but cost a lot of $$$. I hate doctors more than I ever have in my life, but I need them, because most labs won't run tests without referrals. Human health is just a business now, most don't give a shit unless its something obvious like a broken bone or the gash you are bleeding from.