- Pinworm infections are caused by worm-like parasites that infect humans' intestines and rectal/anal areas.
- Young children and their household members are at risk for pinworm infections.
- Pinworms are visible. They range in size from 2-13 mm, are white, and resemble a worm but the pinworm eggs are small, transparent and can be seen only with a microscope.
- Pinworm infections are spread person-to-person by ingesting pinworm eggs that have contaminated fingers, bedding, clothing or other items.
- The symptoms of pinworm infection are discomfort and itching in the anal/rectal area. Children especially will scratch the rectal/anal area, get eggs on their fingers or underneath their fingernails and transport the infective eggs to bedding, toys, other humans, or back to themselves. 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 rectal/anal area where females deposit about 10 to 15 thousand eggs.
What is pinworm infection in humans?
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 in both the lay and medical literature. These parasites are also termed seatworms or threadworms, and the infections is medically termed enterobiasis or helminthiasis. Pinworms and other parasitic worms (which, as a group, are termed helminths) feed off of the host animal by adsorbing nutrients from the host animal. Pinworm infections are the most common helminth infection that occurs in the US.
Pinworms in children
School-age children have the highest rates of pinworm infection. They are followed by preschoolers. Institutional settings including day care facilities often harbor cases of pinworm infection. Sometimes, nearly half of the children may be infected.
Pinworms in adults
Pinworm infection often occurs in more than one family member. Adults are less likely to have pinworm infection, except for mothers of infected children. However, adult sexual partners can transfer the eggs to each other.
The pinworms are white, can be seen with the naked eye (no magnification) and are about the length of a staple (about 8-13 mm for female and 2-5mm for male worms). The eggs that are laid by the female worms are not visible as they are about 55 micrometers in diameter and are translucent (see Figure 1).
The male and female worms live for the most part within the rectum of humans but have a life cycle in humans that involves rectal/oral transmission (see Figure 2).
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 especially will scratch the rectal/anal area, get eggs on their fingers or underneath their fingernails and transport the infective eggs to bedding, toys, other humans, or back to themselves. 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 rectal/anal area where females deposit about 10 to 15 thousand eggs.
How is pinworm infection spread?
Pinworm infection is spread person-to-person. Within a few hours of being deposited on the skin around the anus, pinworm eggs become infective (capable of infecting another person). They 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. However, eggs on bedding or other objects that are touched while the eggs are still viable can cause infection or reinfection of people.