I learned how to do flotation when I was working on a horse farm in MT. I used sugar or salt in a test tube of water to saturate it very highly and then I'd have a manure sample in the tube and stuck a clean slide on top and the parasite eggs would float up and cling to the slide (this is all I remember from many years ago). I'd put the slide under the microscope and count parasite eggs. I imagine that sort of thing is what they do for human parasites. My poor mother had to boil our underwear and maybe sheets too for a couple of weeks. My brother was little enough to be using a potty chair on the floor and that's how our mother spotted the pinworms. She had a degree in medical technology and our father was a pathologist so from their education in parasitology they knew what to do. They came in at night when I was asleep with a flashlight trained on my butt and I woke up to hear them whispering "there's one" and "there's one"--they knew the worms came out at night to lay eggs. So then it was off to Mayo because we could stay with grandparents for the procedure.