What are the symptoms of pinworm infection? What causes pinworm infection? Get the facts about this common intestinal worm infection.

Overview of Pinworm Infection

Pinworm infection is the most common type of intestinal worm infection in the United States and one of the most common worldwide. Pinworms are thin and white, measuring about 1/4 to 1/2 inch (about 6 to 13 millimeters) in length.

Pinworm Characteristics

An adult pinworm generally is 1/4 to 1/2 inch (about 6 to 13 millimeters) in length. The most common symptom of infection is anal itching, particularly at night, as worms migrate to the host’s anal area to lay their eggs.

Pinworm Egg Laying

While the infected person sleeps, female pinworms lay thousands of eggs in the folds of skin surrounding the anus. Most people infected with pinworms have no symptoms, but some people experience anal itching and restless sleep.

Pinworm Infection Occurrence

Pinworm infection occurs most often in school-age children, and the tiny (microscopic) eggs are easily spread from child to child. Treatment involves oral drugs that kill the pinworms and thorough washing of pajamas, bedding and underwear. For best results, the entire family should be treated.

Pinworm Infection Symptoms

What are the symptoms of pinworm infection? Symptoms may include itching of the anal or vaginal area, insomnia, irritability, teeth grinding and restlessness, and occasional stomach pain and nausea. Pinworms often cause no symptoms.

When to See a Doctor

When should you see a doctor for pinworm infection? Consult your doctor if you have severe anal itching, especially at night.

Causes of Pinworm Infection

What causes a pinworm infection? Accidentally swallowing or breathing in pinworm eggs causes a pinworm infection. The tiny (microscopic) eggs can be carried to your mouth by contaminated food, drink or your fingers. Once swallowed, the eggs hatch in the intestines and mature into adult worms within a few weeks.

Female pinworms move to the anal area to lay their eggs, which often results in anal itching. When you scratch the itchy area, the eggs cling to your fingers and get under your fingernails. The eggs then get transferred to other surfaces, such as toys, bedding or toilet seats. The eggs can also be transferred from contaminated fingers to food, liquids, clothes or other people.

Pinworm eggs can survive for two to three weeks on surfaces.

Risk Factors for Pinworm Infection

What are the risk factors for pinworm infection? Risk factors include being young, with pinworm infections most likely to occur in children ages 5 to 10. The tiny (microscopic) eggs are easily spread to family members, caregivers, or other children at school or child care centers. Pinworm infections are uncommon in children younger than age 2.

Living in crowded spaces is another risk factor, as people who live in institutions are at higher risk of developing pinworm infections.

Complications of Pinworm Infection

Can pinworm infections cause serious problems? Typical pinworm infections don’t cause serious problems. In rare circumstances, heavy infestations can cause infection of female genitals. The parasite can travel from the anal area up the vagina to the uterus, fallopian tubes and around the pelvic organs, causing problems such as inflammation of the vagina (vaginitis) and inflammation of the inner lining of the uterus (endometritis).

Although rare, other complications of a pinworm infection may include urinary tract infections, weight loss, and infection of part of the abdomen (peritoneal cavity).

Preventing Pinworm Infection

How can you prevent the spread of pinworm infection? Pinworm eggs can cling to surfaces, including toys, faucets, bedding and toilet seats, for two weeks. Besides regular cleaning of surfaces, methods to help prevent the spread of pinworm eggs or to prevent reinfection include:

• Washing the anal area in the morning, as pinworms lay their eggs at night. Showering may help avoid possible re-contamination in bath water.
• Changing underwear and bedding daily to help remove eggs.
• Laundering bedsheets, pajamas, underwear, washcloths and towels in hot water to help kill pinworm eggs, and drying on high heat.
• Avoiding scratching the anal area, and trimming fingernails to reduce space for eggs to collect.
• Washing hands well after using the toilet or changing a diaper, and before eating, to reduce the risk of getting or spreading an infection.