Enterobiasis is a parasitic condition involving the small roundworm Enterobius vermicularis. It is frequently asymptomatic, and not a dangerous disorder, but it can be unpleasant. Other names include pinworm infection, and seatworm infection. It is the most common worm infection worldwide. It is estimated that 200,000,000 people may be infected.

Enterobiasis is contracted by swallowing the minute eggs of Enterobius vermicularis. These hatch in the small intestine, and can grow up to 1cm long. The adult female emerges at night to lay her eggs around the anus. Each female is capable of producing up to 10,000 eggs. It is sometimes possible to see the female worm if the anus of the individual concerned is inspected at night-time.

The laying of eggs causes itching in the anal area, which may lead to scratching, and eggs being transferred to the hand. The eggs may be deposited on a door handle or other communal object by an infected individual. Infected individuals often swallow the tiny eggs that become caught under their fingernails, leading to reinfection. The eggs may also be inhaled when disturbed from the underwear or bedclothes of the infected.

If a pinworm infection is suspected and other possible causes of irritation, such as haemorrhoids have been discounted the best diagnostic method involves sticky tape. If this is placed against the anal opening first thing in the morning some of the eggs present will be stuck to it. Conclusive diagnosis can then take place following a miscoscope investigation of the tape.

Treatment is simple, involving the use of drugs such as mebendazole. A much bigger problem is in preventing reinfection. Becuase of the ease with which cross-infection can occur it is reccomended that all people living in the same house should recieve drug treatment. Meausures that should be taken to prevent reinfection include:

  • Morning showers
  • Regular bed-linen changes.
  • Preventing contact with the anal area
  • Keeping fingernails short.
  • Washing hands before eating.

Collins Medical Dictionary
Animals Paristic in Man: Geoffrey Lapage