Recently, a reader wrote to us with one of the simplest questions we’ve ever received: what do pinworms (sometimes spelled “pin worms” – incorrectly) look like? To call this question simple is not to call it bad or insignificant – it’s important to know what pinworms look like if you suspect that you (or your child) have pinworms (they only afflict people), and in any case, we rather enjoy an easy question. Since the reader was exclusively interested in the appearance of pinworms, we’ll limit our remarks to this topic. If you would like to know more about these bothersome creatures in general, we encourage you to check out one of our previous articles about pinworms.

First, pinworms are very small. They are usually under a half an inch in length, and they are extremely thin. They basically look like short pieces of fine thread, or, if their body was rigid, we suppose they would probably look a lot like pins. Obviously, their name and appearance are not coincidental. Because they are so thin, they resemble horsehair worms, although they are much smaller, and they would seem to be proportionally shorter than horsehair worms as well (because horsehair worms can be very long despite their extremely thin body).

Even though they are small, pinworms can be seen by the naked eye, which is fortunate from the standpoint of diagnosing the problem. What is less fortunate is where you might observe pinworms: they are found in the lower area of the large intestine, right inside or possibly around the anus, where the females lay their eggs at night (this is what leads to increased irritation at night), as well as in the stool of afflicted people. They are a yellow-white color, which also makes them easier to see.

If you suspect that you or your child has pinworms, address the problem with haste. They are highly contagious, but eminently curable, so talk to your doctor if you think pinworms are afflicting you and/or your family.