jeeperscreepers
It's a fecal test. Hookworm is described as "self-limiting" because the worm cannot complete it's life cycle in a human host. If you were to, say, sit on the ground near puppies, kittens, etc. they are able to burrow through the skin. Then they migrate under the skin until reaching - the lungs? Coughed up, swallowed, mature to adults in the intestine.
I don't think it's possible to have a hookworm infection for many, many years without constantly reinfecting yourself. I'm not sure how long an adult hookworm can survive in a human.
Strongyloides is much different because the female produces eggs, which are capable of maturing to larva in the intestine, without a male.
If you are constipated that leaves the eggs in the intestine longer and contributes to the problem of autoinfection because the eggs can actually hatch and mature in the intestine. Unlike hookworm.
It's a friggin nasty worm.