Pinworms (Enterobiasis) in Kids and Adults
Pinworm definition and facts
- Pinworm infections are caused by worm-like parasites (Enterobius vermicularis) that infect humans' intestines and rectal/anal areas.
- Young children, school-aged children, and their household members, including adults, 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, bed linens, clothing, nightclothes, or other items.
- The major signs and 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.
- Other signs and symptoms may include:
- Discomfort in the anal and/or vaginal area
- Rash or skin irritation around the anus or vagina
- Insomnia or difficulty sleeping and/or restlessness due to irritation of the skin
- Pinworms can often be seen on the anal skin or in the stools, sometimes detected in the vagina, and may produce some vaginal discharge
- Some infected individuals may have abdominal pain.
- Some infected individuals can get secondary bacterial infections from intense skin scratching.
- Infrequent infection of the ureters and/or bladder may cause dysuria or bladder discomfort.
- Pinworm eggs hatch into larval forms in the small intestine and then progress to the large intestine where they mature, mate, and progress to the rectal/anal area where females deposit about 10,000-15,000 eggs.
- Diagnosis may be done by a "tape test" and/or by visualizing pinworms in the stools or on the skin near the anus or in the vagina.
- Most primary care or pediatric doctors can diagnose and treat patients with pinworms.
- Several drugs may cure a patient with pinworms when administered over time.
- Natural and/or home remedies are available, but patients should check with their doctor before using them.
- Good hygiene can help prevent pinworm infections.
What are pinworms?
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 are medically termed enterobiasis, oxyuriasis, or helminthiasis. Pinworms and other helminthic 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 only infect humans. Dogs, cats, or other animals cannot become infected.
Who gets pinworms?
Pinworm is the most common parasitic worm infection in the United States, and the majority of pinworm infections worldwide occur in children, in temperate climates.
Pinworms in children
The highest rates of pinworm infection occur in school-age children. They are followed by preschoolers. Institutional settings including daycare facilities often harbor multiple individuals (adults and children) with pinworm infections. Sometimes, nearly half of the children may be infected in a daycare facility.
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. Pinworms also may infect the vagina and urethra.
What are the symptoms of pinworms in children and adults?
If symptoms are present, they are similar in both children and adults. The signs and symptoms may include one or more of the following:
- Intense (pruritus) around the anus and/or vagina
- Discomfort in the anal and/or vaginal area
- Rash or skin irritation around the anus or vagina
- Insomnia or difficulty sleeping and/or restlessness due to irritation of the skin
- Pinworms often can be seen on the anal skin or in the stools, sometimes detected in the vagina, and may produce some vaginal discharge
Less common symptoms include:
- Abdominal pain
- Secondary bacterial infections from intense skin scratching
- Infrequent infection of the ureters and/or bladder may cause dysuria or bladder discomfort
Many infected children and adults have few or no symptoms but, if the infection is heavy, the symptoms can be correspondingly more severe.
What do pinworms and their eggs look like (pinworm pictures)?
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 10,000-15,000 eggs.
How do you get pinworms?
Pinworm infection is spread person to person. The symptoms of pinworm infection are caused by the female pinworm moving and laying her eggs, and this usually occurs at night. 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 nightclothes, bed linen, 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.
Can you get pinworms in the vagina?
Yes, pinworms can infect the vagina (about 20% of infected girls). Infrequently, the pinworms can go on to infect the Fallopian tubes and other structures.
