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Pinworms are a type of
parasite that lives in the
digestive system of humans. They are common throughout the world, especially in
Adult pinworms look like small, white threads
that are no more than
0.5 in. (12.7 mm) long. You
need a microscope to see the eggs.
Pinworm infections are spread from human to human. Pets don't get pinworms and can't spread them to humans. Most people get pinworms by swallowing the worms'
eggs. This happens when someone with pinworms scratches around the
anus, gets eggs on his or her hands (or under the
fingernails), and touches you or a surface that you later touch. When eggs get
on your hands or food and then you eat, the eggs go into your mouth. And they
move into your stomach and then to your rectal area.
turn into worms in about a month. A pinworm crawls out of the body during the
night and lays eggs on the skin around the anus. The wiggling motion when the
worm lays eggs may irritate the skin and cause itching.
spread easily in families, day care centers, schools, camps, and other places
where groups of people live. If one person in your family has pinworms, others
probably do too. Pinworm infections can happen to anyone. They are not related
to being unclean.
The most common sign of pinworms is itching
around the anus. Many people with pinworm infections have no symptoms and may
never be aware of the infection. In rare cases, itching becomes severe and may
cause restless sleep, loss of appetite, and
Pinworms don't usually cause
serious health problems, and they do not carry disease. But it is possible to
get a skin infection from scratching around the anus.
incubation period—the time from first contact with eggs until symptoms
appear—is usually 1 to 2 months or longer.
Your doctor can find out if you have a pinworm
infection by asking about your past health and checking the skin around your
anus. He or she may ask you to collect a sample from around the anus by using a
piece of clear, sticky tape. This piece of tape will be put under a microscope
to look for pinworm eggs.
You can treat pinworm infections with
over-the-counter and prescription medicines. These
medicines can help keep you from getting infected again and from spreading
pinworms to other people.
To limit the
chances of getting pinworms or of spreading them to others:
If family members get pinworms again, all family members
may need to take medicine to kill pinworms.
Learning about pinworms:
infections are usually caused by swallowing the eggs of the pinworm (Enterobius vermicularis) after coming in contact with an
infected person or with an object that has eggs on its surface. Infection can
also be spread when a person inhales airborne eggs, but this is rare. It's also rare for pinworms to spread to people in a swimming pool.
In some cases, pinworm infection persists because eggs hatch outside the anus and the
young worms crawl back inside the body.
Pinworms do not
usually cause any symptoms beyond minor itching around the
anus. Many people with pinworm infections have no
symptoms and may never be aware of the infection.
The most common symptoms of pinworm infection
in children include:
Other possible symptoms that may be present but are much
less common include:
The above symptoms may result in
The time it takes from when
the eggs first enter your body to the time that an adult female pinworm lays
new eggs is about one month. The eggs of
pinworms get into the body through the mouth and
develop into worms in the lower
digestive system. They begin growing in the small
intestine and move into the large intestine, where
they become adult worms. The worms live by eating nutrients found in your
Female pinworms crawl out of the body and lay their
eggs during the night on the skin around the
anus. The female worm's wiggling motion when laying
eggs is believed to irritate the skin and cause itching. The eggs have a damp,
sticky covering, so when children scratch the skin around the anus, eggs stick
to their fingers and get stuck under their fingernails. The eggs can then be
transferred into their mouths or onto objects such as faucets and food. The
eggs can also stick to clothing, bedding, and furniture. The eggs can live 2 to 3 weeks outside the body.
Pinworms are spread when
someone with pinworms scratches around the anus, gets eggs on his or her hands
(or under the fingernails), and touches another person or an object. Infection
can occur when:
A person with pinworms can be reinfected by any of the
means listed above or when eggs hatch on the skin around the anus and the young
worms (larvae) crawl back into the body.
Pinworm infection is
contagious as long as living pinworm eggs are spread to and swallowed by
someone. Because the medicine to treat pinworm infection kills adult worms but
not pinworm eggs, a person who has received one treatment for pinworms can
still spread the infection. This is why it is important to
wash your hands often when you know that someone is infected. A second
treatment with medicine is usually needed about 2 weeks after the initial treatment to
kill any worms that have hatched during that time.
pinworms are rare. The most frequent complications are bacterial infection
around the anus or of the skin in the genital area. This is usually because of
skin irritation or scratches from itching in these areas.
Factors that increase the
risk of being infected by
Factors that increase the risk of spreading pinworm
Call your doctor if:
Watchful waiting is not appropriate
when a person has symptoms of a pinworm infection. Although pinworm infections
are usually mild and do not cause any serious health problems, treatment should
be considered because it helps stop the spread of the infection to others and
helps prevent reinfection.
Watchful waiting may not be appropriate
for family members of a person infected with pinworms. If one member of a
family has a pinworm infection, it is very likely that other members also are
infected. This is very important if a family member is pregnant. A pregnant
woman may not be able to take pinworm medicine, and treating all other members
of the household may decrease the likelihood of her getting the infection. Some
doctors recommend treating all members of the family to help prevent
reinfection and the spread of infection.
Health professionals who can diagnose and treat pinworm
complications of pinworm infection develop, you may
need to see a specialist who deals with conditions affecting the body system
involved, such as:
To prepare for your appointment, see the topic Making the Most of Your Appointment.
pinworm infection is suspected, the doctor will ask about your or your child's medical history and do a physical exam. During
the physical exam, your doctor will examine the skin around the
anus for redness and irritation. Also your doctor may
ask you to collect a sample by using a piece of transparent adhesive tape. This
test, sometimes called a
cellophane or "Scotch tape" test, involves pressing a
piece of transparent tape on the skin around the anus in the morning
before you or your child gets up or bathes. This piece of tape is then viewed
under a microscope to look for pinworms and their eggs. The doctor may ask you to repeat the test a few times.
Other tests may be done if the physical exam and
cellophane test have not shown pinworms and an infection is still
complication of pinworm infection is suspected, more
tests may be done. The specific tests that are needed will depend on the
person's symptoms and the part of the body that is affected.
Pinworms can be
successfully treated with:
Pinworms are treated with medicine when:
If severe itching is present, your doctor may prescribe a
soothing cream to be applied to the anal area. If complications of pinworm
infection develop, additional treatments may be needed.
Some doctors suggest treating
all close contacts of a person with pinworms even if there are no symptoms.
Treating contacts with over-the-counter medicine can help prevent reinfection
and the spread of pinworms to other people. This is especially important in
households where pinworm infections come and go.
Treatment of all
household members may be recommended if someone in the household is pregnant,
breast-feeding, or younger than 2. These people may not be able to take pinworm
medicine, and their chance of infection may be lower if all other members of
the household are treated.
Many doctors suggest a second treatment 2 weeks after the first treatment to kill
any adult worms that may have hatched from eggs during that time. Pinworm
medicine does not kill pinworm eggs.
Hand-washing is the best way to help prevent pinworm infections. For more information about how to prevent reinfection and the spread of infection to other members of the household, see the Home Treatment
section of this topic.
For people with
pinworm infections, home treatment is very important
to prevent reinfection and the spread of infection to other members of the
household. Good home treatment includes the following measures:
Preventing the spread of infection is
especially important in households that include children younger than 2 or
pregnant women, because they may not be able to take medicine for
Medicine is often used for
pinworm infections that are causing symptoms such as
itching. Over-the-counter and prescription medicines come in liquid, chewable tablet, and pill forms. Most pinworm
infections are cured with medicine.
Because medicines do not kill
pinworm eggs, two doses are usually needed, 2 weeks apart. The second dose is
necessary to kill any worms that may have hatched from eggs after the initial
treatment. In some cases of reinfection, 4 to 6 treatments (spaced 2 weeks
apart) are needed.
Do not use other medicines to treat pinworms without
first speaking to your doctor.
Pinworm medicine is not
recommended for use by pregnant women, breast-feeding women, or children
younger than 2 without talking to a doctor about the risks and benefits of
medicine. These groups are advised to use measures to prevent reinfection
rather than using medicine. For more information, see the Home Treatment
section of this topic.
The American Academy of Pediatrics (AAP) offers a
variety of educational materials about parenting,
general growth and development, immunizations, safety, disease prevention, and more. AAP guidelines for various conditions and links to other
organizations are also available.
U.S. Centers for Disease Control and Prevention (CDC)'s website on parasites offers information on diseases caused by parasites. It provides information on topics such as malaria, neglected tropical diseases, and parasitic infections in the United States. There are also links to related information, such as a glossary and a site on healthy water, and other references and resources, such as statistics on parasitic diseases.
This website is sponsored by the Nemours Foundation. It
has a wide range of information about children's health—from allergies and
diseases to normal growth and development (birth to adolescence). This website
offers separate areas for kids, teens, and parents, each providing
age-appropriate information that the child or parent can understand. You can
sign up to get weekly emails about your area of interest.
The National Institute of Allergy and Infectious
Diseases conducts research and provides consumer information on infectious and
American Academy of Pediatrics (2009). Pinworm infection (Enterobius vermicularis). In LK Pickering et al., eds., Red Book: 2009 Report of the Committee on Infectious Diseases, 28th ed., pp. 519–520. Elk Grove Village, IL: American Academy of Pediatrics.
Other Works Consulted
Drugs for parasitic infections (2010). Treatment Guidelines From The Medical Letter, 8(Suppl): e1–e20.
Hotez PJ (2009). Parasitic nematode infections. In RD Feigin et al., eds., Feigin and Cherry's Textbook of Pediatric Infectious Diseases, 6th ed., vol. 2, pp. 2981–2996. Philadelphia: Saunders Elsevier.
Van Voorhis WC (2010). Helminthic infections. In EG Nabel, ed., ACP Medicine, section 7, chap. 35. Hamilton, ON: BC Decker.
August 30, 2012
John Pope, MD - Pediatrics & Susan C. Kim, MD - Pediatrics
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