Pinworm Life Cycle

Introduction:

Pinworms, also known as Enterobius vermicularis are parasitic worms that fall under the family Oxyuridae, the phylum Nematoda and the order Rhabditida. Pinworms are most commonly found in the human intestine, and more prominent in children. These worms are also called seat worms or threadworms and they measure up to 13 mm in length. They appear to be thread-like, white in colour and thin in shape. The male pinworms measure up to 5 mm and the female pinworms measure up to 13 mm length in size.

Pinworms mostly reside in areas of the large intestine of humans but are sometimes found in the small intestine. The life expectancy of these worms is approximately four to eight weeks.

Let’s look at their life cycle to get a better understanding.

Life Cycle of Pinworm

1) The Egg – Stage 1 –

After the adult male and female pinworms have mated, the female pinworm migrates to the anus to deposit her eggs. A gravid female pinworm is able to lay 10,000 to 15,000 eggs. The laid eggs cause severe itching in the anal area, forcing the human host to scratch that area rigorously. In the process of rigorous scratching, the eggs get transferred under the fingernails of humans. When the fingers come in contact with the mouth, the eggs enter and reach the small intestine of the host. After this, the eggs develop and hatch as larvae in the small intestine.

2) The Larvae – Stage 2 –

After the pinworm eggs are ingested, they hatch into larvae in the small intestine but live in the colon of the host. The larvae inside the eggs become infective in about 4 to 6 hours under favourable conditions. The larvae migrate to the large intestine and attach themselves in the wall of the colon. The larvae search for the nearest exit like the anus. Some of the hatched larvae migrate from the anus back inside the rectum.

3) The Adult – Stage 3 –

The time period from ingestion to the oviposition of the adult female pinworm is approximately one month. The gravid female pinworms migrate outside the anus during the night, laying her eggs at the rim of the anus. The adult pinworms usually establish themselves in the colon of the host.

Conclusion:

More than one billion people have been affected with pinworm infection all across the globe. The life cycle of a pinworm usually requires a period of 15 to 43 days. These worms attack the intestines and the rectal regions of the human host. A pinworm infection causes disturbed sleeping patterns, rash or skin irritation and abdominal pain.