A Worm With a Rapid Wriggling Movement in the Right Colon

Edgar Jaramillo, MD, PhD


December 04, 2001


Pinworm (the causative agent of human enterobiasis) is the most common parasite infecting humans worldwide. The disease is more prevalent among children, but adults may also be affected. Perianal itching is the most common complaint, although many infected individuals are asymptomatic.

Adult pinworms "live" in the lumen of the human colon, and nocturnally migrating females deposit eggs on the perianal skin. Infestation occurs by finger transfer of eggs. Contaminated clothes, bed linens, or inhalation and swallowing of airborne eggs are other common routes. The standard method of diagnosis involves the demonstration of eggs obtained in the early morning by applying an adhesive tape to the perianal skin.

The striking movement and characteristic shape of pinworms make the endoscopic diagnosis quite direct. Parasites may be suctioned or grasped with a biopsy forceps for diagnostic purposes. The differential diagnoses may include anisakiasis and trichocephaliasis.

The utility of medical treatment in asymptomatic patients has been questioned by some authorities because of the high prevalence of this harmless infestation, which has a high rate of recurrence.

A single dose of mebendazole followed by a repeat dose 2 weeks later is the treatment of choice, with a cure rate of 90% to 100%. Treatment of family members is recommended because they may be reservoirs of infection.