The common name for the oxyuris equi is the pinworm. Pinworms often use humans as their hosts, and this can make them a little more irritating than other parasitic worms - to humans, at least. It takes a load off of cows and horses because this is one they don’t have to worry about.
This particular worm has one side effect that makes a lot of people uncomfortable: they make the anus itch. This is because of a goop the worm secretes when inside of a host. There are a lot of risk factors, oddly. One of them is simply going to school; the sanitation in some public schools isn’t the best. Other risk factors include touching somewhere the eggs have deposited, or touching somewhere an infected person has touched after itching.