Pinworm

Causes and Risks:

The organism causing pinworm infection is a small whitish worm called Enterobius vermicularis. It is visible to the naked eye. E. vermicularis is found throughout the United States. The incidence varies and is higher in urban areas and crowded settings. The parasite is easily spread. Pinworm infections appear to come in cycles with years when very few infections are seen and then years when a high infection rate is seen.

Adult pinworms live in the large intestine (cecum and colon). Eggs are laid outside the anus during the night and are spread from person to person from contaminated clothing, articles, and hands. Eggs can also drift through the air where they are inhaled or swallowed. The eggs hatch in the small intestine and travel to the large intestine where they mature. Institutionalized children, large groups of children as in schools, and children with poor personal hygiene are at risk for contracting an infestation. The incidence is about 20 percent of children in the U.S., with a higher incidence in institutional settings.

Prevention:

Good personal hygiene with emphasis on washing hands after using the bathroom is mandatory. Children should be taught not to put their hands or other objects in their mouth. Since the infection can be spread by airborne eggs, once a diagnosis is made, the person should be treated and bedding and underwear should be laundered using hot water and a mild bleach solution. Occasionally, the health care provider will treat other family members or very close contacts prophylactically.

Symptoms:
  • intense itching around the anus
  • irritability (usually caused by itching and interruption of sleep at night)
  • sleep disturbance (usually due to itching that occurs during the night when the adult worms migrate out through the anus to lay their eggs.
  • decreased appetite and weight loss (this is uncommon but can occur in severe infections)
  • vaginal irritation or discomfort in young girls (if an adult worm enters the vagina rather than the anus)
  • excoriation and irritation of the skin or infection around anus from constant scratching



Signs and Tests:

Pinworms can often be spotted after the child has gone to sleep. The anal sphincter relaxes and the worms crawl out onto the skin to lay their eggs.

Tape test:

  • Eggs can be seen under the microscope. A sample is collected by pressing a piece of cellophane tape against the skin around the anus, then sticking the tape to a microscope slide for later observation. This should be done in the morning before bathing or using the toilet as the eggs may be inadvertently removed. The slide is then placed under the microscope and observed for pinworm eggs. The presence of eggs is diagnostic.



Treatment:

A medication to kill the worms is prescribed. Pyrantel pamoate, Mebendazole (typically a single dose treatment) Pyrvinium pamoate, and Piperazine are some of the medications that may be prescribed.

Some authorities feel that treatment is unnecessary, because the infestation rarely causes problems and reinfestation is likely. Measures to completely eliminate infestation within a family involve treating each family member and retreating in two to three weeks.

General measures to control infestation are washing hands before meals and after use of the toilet, keeping fingernails short and clean, laundering all bed linen twice weekly, and cleaning toilet seats daily. Avoid scratching the infected area (area around the anus) as this contaminates the fingers and everything else that they subsequently touch. Keep hands and fingers away from the nose and mouth unless they are freshly washed. Carry out these measures while family members are treated with medication.

Prognosis:

Pinworms cause little damage and can be eradicated easily with proper treatment. Full recovery is expected.

Complications:

  • salpingitis (extremely rare)
  • worms may enter the peritoneal cavity through the female genital tract (extremely rare)
  • vaginitis
  • emotional disturbance
  • reinfestation



Call Your Healthcare Provider:

Call for an appointment with your health care provider if symptoms of pinworms develop or you have seen pinworms on you child or in the bedding.


Pinworms are a common problem in children and may spread to adults (typically the parents or other care-givers). The eggs may be easily seen under a microscope. To obtain a sample, a piece of Scotch-tape is pressed against the patient's anal opening. The sticky side of the tape picks up the pinworm eggs and the tape is then stuck to a microscope slide. The eggs can be viewed under the microscope. (Courtesy of the Centers for Disease Control.)



Pinworms are a relatively common problem among children. They are easily transmitted and sometimes appear as mini epidemics in classrooms. This is a photomicrograph of the head of a pinworm.