General Information

Enterobiasis (sometimes called oxyuriasis) is the condition that arises from infestation with Enterobius vermicularis, commonly known as pinworm, seatworm, or threadworm. E. vermicularis is one of the most common helminthes and is certainly the most prevalent gastrointestinal nematode in humans. The pervasiveness of pinworm is largely related to its broad geographic distribution around the world, especially in temperate areas such as the United States and Western Europe. While enterobiasis occurs among adults, it is more often associated with pediatric populations and it is between children that the helminthes are typically spread.

In addition to E. vermicularis, it has been suggested that another pinworm species known as Enterobius gregorii Hugot also causes enterobiasis. Although evidence of this species has been recorded in Africa, Asia, and Europe, large doubt remains as to whether this species is distinct from E. vermicularis, and many scholars believe it may just be a more immature form of the universally recognized nematode.

http://www.horseit.com/en/Health2001/worming/WormTypes.htm

Enterobius vermicularis exhibits a large sexual dimorphism. While the female worms are typically 8-13 mm long and 0.5 mm wide, the males are usually only 2-5 mm long and 0.2 mm wide. The female E. vermicularis is distinguished by its blunt lateral cephalic alae (“nose”) and its narrow and sharply-pointed tail, for which it gets the name “pinworm.” The worm has a characteristic white color with a slight yellow tinge.