Question:

I can remember years ago hearing about lots of kids who got pinworms. How did they get them? How does a person know if they've got them?

Answer:

Pinworms are as common among schoolchildren and preschoolers today as they were years ago. The tiny, parasitic worms are thin and small - about the length of a staple.

Unlike most parasitic worms, pinworms don't invade the body and cause any particular harm other than rectal itching. The eggs are swallowed and hatch in the small intestine. From the small intestine, the pinworms larvae migrate to the large intestine, where they live. The female pinworms move on to the rectal area to lay their 10,000 to 20,000 eggs. This is what causes the intense rectal itching that triggers scratching, which in turn transfers the eggs. They can live on various surfaces for two to three weeks, and be accidentally ingested.

Children are most vulnerable to the parasite because they ingest the microscopic eggs when they put their fingers in their mouths, bite their nails, or fail to wash their hands, especially after defecating. Second-most vulnerable: their parents.

If a child has rectal itching (especially at night), doctors advise parents to perform the "scotch tape" test: The sticky adhesive surface is used to obtain eggs, which can then be seen under a microscope.

There is a simple, two-dose cure: one antiparasitic dose kills all the worms, and a second, two weeks later, kills any larvae that hatched from eggs. Transient rectal itching can be treated with numbing cream.