It's possible to spot threadworms in the stool after a bowel movement ... Threadworms aren't the only worms (helminths) that invade humans. Hookworms, for example, affect about 470 million people ...

but the worms can enter through any part of the skin. It cannot spread between humans. When the larvae moves under the skin, the body's immune system reacts, causing the inflamed, bumpy red lines ...