Itchy Bottom and Pinworms

In: Digestive System|Parasites

20 May 2011

What is  a  Pinworm?

Pinworm , also called Enterobius vermicularis, is a parasite that lives in the human intestinal tract . Its found worldwide .

What do they look like?

The adults are small white and short that have a pointed pin like tail. The female is much larger than the male measuring 8 – 13 mm long and 0.3-0.5mm thick  as compared to the male which is 2-5 mm and 0.1 -0.2 mm thick. In The pregnant female worm , literally the whole body is full of thousands of eggs.

Life cycle

The Pinworm lives its whole life cycle in the human host . It has no intermediate host .The adult worms live in the appendix and upper part of the colon . The male worms do not migrate and die soon after mating . The female worm migrates down to the lower part of the colon to the rectum , at night when the host  ( infected person) is in bed, the worm comes out through the anus and crawls around the anus and surrounding genital skin and lays its sticky eggs . The worm may return and come back again to lay more eggs , it may also wonder around the vagina and uterus .

A single worm lays about 5000 – 17000 eggs . The egg is colorless and oval but slightly elongated . The outer layer of the egg is sticky making it adhere to clothing and skin .The egg hatches and becomes infectious 6 hrs after being laid on the skin . If conditions are cool and moist the egg can survive for about 2 weeks .

If the eggs are  swallowed ( especially after scratching and eating without washing hands or nail biting  ) they hatch in the intestine . It takes 2 weeks – 2 months from the the time the eggs are swallowed till the time the time the female worm becomes pregnant.

Signs and Symptoms of pin worms

  1. More common in children
  2. More common in females
  3. Intense irritation and itchiness in the perianal area
  4. Disturbed sleep at night
  5. Rashes in the anal region due to scratching
  6. Vaginal discharge

Diagnosing  pin worm

  1. History of perianal itchiness is one clue , then of course swabs are taken from the skin around the anus in the morning before bathing or going to the toilet and sent to a lab to check for eggs under a microscope .
  2. Another way is called the scotch tape method , where the sticky side of the tape is placed out and the non sticky side along one side of a tongue depressor and the sticky side is allowed to stick to the skin around the perianal skin and the sample sent to a lab where eggs can be seen on the sticky side of the tape under a microscope .
  3. Sometimes the eggs can also be found under the finger nails , on the surface of stools or the adult can be  found crawling out at night on the skin .

Treatment and Prevention

  1. Several drugs like Pyrantal Pamoate , Mebendazole , Piperazone can be taken as a single dose or 2 weeks .
  2. Clean all bed sheets
  3. Cut finger nails
  4. Wash hands before eating
  5. Wear loose clothing
  6. Practice good hygiene
  7. Treat all individuals in groups




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General health blog enables you to find useful and interesting facts about many health topics. Written by Dr. Sumaira Khan, this blog is updated regularly and provides reliable information which is made easy to understand for everyone. please feel free to leave any comments or questions.