What are pinworms?

Pinworms are a type of parasite that infects the intestines. They are common throughout the world.

Adult pinworms are very small, less than a half inch, and look like little white threads. Pinworm eggs are so tiny, you'd need a microscope to see them.

What causes them?

Pinworms are spread from person to person. Most people get infected by touching someone who has pinworms or touching something the infected person has touched. Anyone can get pinworms, but they are most common in children.

Pinworms are usually spread like this:

• Pinworms infect the intestines. Then the pinworms lay eggs around the anus.
• The eggs around the anus can cause itching. If the child scratches the area, the eggs can get on the child's fingers and get stuck under the fingernails.
• The eggs then stick to things the child touches, such as food, clothing, dishes, toys, and furniture. The eggs can live 2 to 3 weeks outside the body.
• When you touch something the child has touched, the eggs get on your hands. Then if you touch your mouth or eat or drink something that has the eggs on it, then you become infected. This starts the cycle over again.

Pinworms spread easily in homes, day care centers, schools, and other places where groups of people spend time together. So if one person in your family has pinworms, others probably do too.

Pets don't get pinworms and can't spread them to humans.

What are the symptoms?

Many people with pinworms don't have symptoms. When symptoms occur, the most common ones are:

• Itching around the anus.
• Restless sleep, because itching is often worse at night.

Pinworms can be annoying. But they don't carry disease, and they rarely cause serious health problems. Sometimes people get a skin infection from scratching.

How are they diagnosed?

To find out if you have pinworms, your doctor will ask about your past health and check the skin around your anus.

The doctor may ask you to do a transparent tape test at home. To do the test, you press a piece of clear, sticky tape on the skin around your anus in the morning before you get up. The doctor will put the tape under a microscope to look for pinworm eggs. You might need to repeat this test a few times.

How are pinworms treated?

You can treat pinworms with over-the-counter or prescription medicine that kills the worms. Treatment can help keep you from getting infected again and from spreading the infection to other people.

You may need a second dose of medicine two weeks later if the infection is not cured. That's because the medicine kills the worms but not the eggs. The second dose will kill any worms that hatch after the first treatment.

Pinworm medicine may not be safe for children younger than 2 or for those who are are pregnant or breastfeeding. So to reduce their risk of infection, a doctor may recommend that all other household members be treated with medicine.

How can you prevent them?

Pinworms spread easily and often come back. To reduce your chances of spreading the infection or getting infected again:

• Wash your hands carefully and often. Teach your children to do the same, especially after they use the toilet and before they handle food.
• Keep your fingernails short, and don't scratch the itch. Wearing gloves at night may help prevent scratching.
• Bathe or shower every day.
• Don't share or reuse towels or washcloths.
• Change your underwear and bedding each morning.
• Wash clothes, bedding, and towels in hot water regularly. Dry them in a hot dryer.

If anyone in your household gets pinworms again, the whole family may need to take medicine.