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Physiology is the study of normal function within living organisms. Well, Enterobius vermicularis or pinworms, are parasites meaning that they use its host body to survive and reproduce. Then, who is its host? In fact, pinworms only have one host and it is the human body. But how does this species enter the human body to infect its host and potentially other human too?

Again, pinworms require a host to complete its life cycle, and without a host, the pinworm cannot develop and reproduce.

Enterobius vermicularis has a simple life cycle, and this is why it is easy to contract a pinworm infection and even less difficult to transmit the infection to others.

The life cycle of pinworms begins with the eggs being ingested by the human host via contact with surfaces that are contaminated with eggs. The eggs hatch to release larvae that begin to grow to a size of about 140 mm and then migrate into the small intestine, and during that migration, it develops into an adult worm. The female pinworm inserts her pin tail into the mucosa for oviposition. Soon, the body of the female pinworm is filled with 11,000 to 16,000 eggs, and the journey to the anus begins. When the female pinworm is migrating out of the anus, she is depositing eggs on the skin around the anus. The process of laying eggs in pinworms is not quite clear. Scientists believe the eggs can be released from the female pinworms by contraction, or it might occur after the death of the female, and her body disintegrates to release the eggs.

What is interesting about this part of the cycle is that the eggs are laid in a sticky, jelly-like substance and along with the wriggling of the female pinworm, causes severe itching — these characteristics are how pinworms can spread to another human host. By secreting an itchy mucus when laying her eggs and moving on the skin, it triggered an urge to scratch the affected area of the anus or vagina. By the fingers or fingernails, the eggs may be transferred to any surface or human that it is touching and if they are touched, they will be transferred to the hands, and eventually, to the person’s mouth leading to a serious risk of swallowing the eggs and becoming infected. This process allows the spread and re-infection of Enterobius vermicularis.

The photo below illustrates the many eggs that female Enterobius vermicularis lay on the skin. These eggs can be picked up by the humans from scratching and resulting in the spread of the infection to other humans. 

The video below shows the movement of a pinworm in a stool sample. The wriggling of the pinworm can cause severe itching for humans leading to scratching. 

As you can see, Enterobius vermicularis do not release a toxin or venom to infected its host as some believed. By just touching a surface that has been contaminated by pinworms egg is all it takes to be infected.  Furthermore, by just the movement of the pinworm and the ability to secrete mucus allow the pinworm to find its new victims. But remember this cycle can be prevented by practicing good hygiene by merely washing your hands.  

Work Cited 

https://biologywise.com/pinworm-life-cycle

https://www.uptodate.com/contents/enterobiasis-pinworm-and-trichuriasis-whipworm#H4

https://www.medicalnewstoday.com/articles/175134.php

Photo: https://www.cdc.gov/dpdx/enterobiasis/index.html

Video: https://www.youtube.com/watch?v=9OYH_UJOsSY