Clinical Information

Enterobius vermicularis, also known as pinworm, is a common intestinal nematode with a worldwide distribution. In the United States, pinworm infection is the most common helminth infection of humans and is most frequently found in young school-age children. Transmission is by the fecal-oral route. Individuals become infected when inadvertently ingesting pinworm eggs from the environment (eg, contaminated objects and surfaces). The eggs then hatch in the small intestine and the adults reside in the lumen of the cecum. Gravid adult females migrate to the perianal area during the night and deposit large numbers of eggs in the perianal area, using a glue-like substance to promote adherence anal skin folds.

Most infections are asymptomatic. When present, the most common symptom is nocturnal pruritus ani (nightly anal itching) from the host inflammatory reaction to the eggs and associated adhesion. With itching, the eggs contaminate the fingers of the host and then spread into the environment to infect others. Autoinoculation is also common. Heavy infections may be associated with irritability, difficulty sleeping, abdominal pain, nausea, and vomiting. Ectopic migration of the adult female worm may also lead to vulvovaginitis, salpingo-oophoritis, peritonitis, and, possibly, appendicitis.

Pinworm infection is best diagnosed through identification of eggs, and occasionally adults, obtained from the perianal skin folds. This is classically accomplished via collection with clear adhesive cellophane tape. The pinworm paddle (eg, SWUBE device) facilitates this collection and provides a safer and more reliable means of collection and examination. To collect eggs with the pinworm paddle, the adhesive side of the paddle is pressed firmly and repeatedly to the perianal region and then returned to its plastic tube for safe transportation to the laboratory. The specimen should be collected first thing in the morning, before the patient bathes or defecates. When the paddle arrives in the laboratory, it is placed on a glass slide and examined using a light microscope for eggs and adult worms. Care must be taken when collecting and examining the specimen, as pinworm eggs are infectious within 4 to 6 hours of being laid. Repeat testing may be recommended to increase the sensitivity of detection in cases of light infection.

Several agents are effective in treating pinworm infection (pyrantel pamoate, mebendazole), and good personal hygiene will prevent transmission of the eggs.