Monday, 28 February 2011


Pinworm is a kind of intestinal parasite and they are belong to the family Oxyuridae and phylum Nematoda. They are scientifically known as Enterobius vermicularis and some people call them ‘seat worm’. Pinworms are mostly infecting people in United States and Europe. Eventough pinworms commonly found in school-aged children, it also can occur in adult as well. Class, race and geographic location do not influence pinworm even in rural areas or urban areas. Their egg can stay alive for twenty days in the moistest environment even in the sewage. As pinworm spread through contamination from host to host, they tend to occur in all people within a household and among people living in close contact. Pinworms are most active at night.
Pinworms Morphology
Adult pinworms are small, white and have threadlike appearance. They can be seen in naked eye and can easily detect. Adult female pinworms are about 0.2 to 0.4 inches (5 to 10 mm) long and 0.5 mm thick with sharp pointed end. As compare to female, male pinworms are much smaller about 2 to 5 mm long, 0.2 mm thick, and have curve posterior end. Figure 1.0 shows the differences between male and female pinworm. Pinworm eggs are very small and colourless which make them invisible with naked eye. But they are visible if they come in clump of thousand eggs. The egg size is about 20 to 30 µm. The egg may contain developing embryo or fully developed larvae which is then grow until 140 to 150 µm inside the host. 
Pinworm Lifecycle
The cycle begins by ingesting contaminated food with the pinworm egg. The egg containing mature larvae will then hatch in small intestine that have proper environment which is slightly alkaline. As the pinworms grow, they establish themselves in the colon where adult female pinworm takes about one month for oviposition. At night, the female pinworm migrates to the perianal region to lay their eggs. This will give itching sensation to patient. The larvae inside the egg develop themselves within 4 to 6 hour under optimal condition. The cycle will continue if no treatment is given to the patient.
Sign and Symptom of Pinworm Infection
Some cases of pinworm infection are asymptomatic. However, the most common symptom of the infection is itching sensation at perianal area. As the sensation occurs at night, it will lead to trouble sleeping. It also gives irritation and discomfort of the vagina in young girl. From constant scratching, irritated skin may break down and this can cause secondary bacterial infection. In severe cases, the patient may lose appetite and weight as the pinworms getting their nutrient from the patient’s body. This symptom is not very common.

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