What causes pinworm?

Pinworm infection is an infection of the large intestine and anal area by a small, white parasite that resembles a “worm.” The medical name for the parasite is Enterobius vermicularis, but it is commonly termed a pinworm. Pinworms are parasites known as helminths that feed off of the host animal by adsorbing nutrients from the host animal. Pinworm infections are the most common helminth infection that occurs in Australia.

Who is at risk of pinworm?

Pinworm infection is common in households with pets and children. School-age children have the highest rates of pinworm infection. They are followed by pre-schoolers. Institutional settings including day care facilities often harbor cases of pinworm infection.

What do pinworms look like?

Pinworms are white, can be seen with the naked eye without need for magnification and are about the length of a staple (about 10 mm for female worms) and half this size for male worms. The eggs that are laid by the female worms are not visible.

The male and female worms live for the most part within the rectum of humans but have a life cycle in humans that involves the oral faecal route.

Spread of pinworm

While an infected person is asleep, female pinworms leave the intestines through the anus and deposit eggs on the skin around the anus. This causes itching and irritation of the surrounding area. Children will scratch the anal area, getting eggs on their fingers or underneath their fingernails and transport the infective eggs to others. The eggs hatch into larval forms in the small intestines and then progress to the large intestine where they mature, mate, and progress to the anal area where females deposit about 10 to 15 thousand eggs. Pinworm can survive up to two weeks on clothing, bedding, or other objects. Infection is acquired when these eggs are accidentally swallowed, usually due to inadequate hand washing by the parents and children.

How is pinworm diagnosed?

Pinworm can be diagnosed by your GP by performing a simple test. Transparent adhesive tape (cellotape) is applied to the anal region. This will often lift off the eggs, and occasionally the worms as well, allowing them to be examined under a microscope. The test is sometimes referred to as “the Scotch Tape test.” The test should be done as soon the affected individual wakes up in the morning (because bathing or having a bowel movement may remove most eggs and parasites). The exam may require several samples for diagnosis.

What is the treatment for pinworm?

The treatment is quite simple, usually a single tablet of mebendazole (Vermox). This can sometimes be repeated a week later or, if infection persists, the medication is given again three weeks later. Some clinicians recommend a treatment regimen of a dose every 3 weeks, 3 times, so that the person has effective drug treatment for about 9 weeks total.

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