Microscopic photography of a pinworm.

The ‘pinworm’ (Enterobius Vermicularis) is an intestinal parasite of the nematoda order, oxyurata. The common name ‘pinworm’ derives from the appearance of its tail, which is long, thin and pointed. Unlike most other nematodes, Enterobius organisms are more common in temperate countries than in the tropics. Enterobius Vermicularis infests more than 400 million people worldwide and is found predominately in temperate or colder climates. 1,2 Although serious clinical disease is extremely rare, pinworm infection carries with it much unwarranted social stigma. 3 Enterobiasis is a familial or institutional infection that has no preference for socio-economic status. This female worm was presented alive in water on a microscopic slide. The worm was visible to the naked eye and was laying eggs; female worms typically measure 8–13mm whereas male counterparts measure approximately 2–5mm. Gravid females emerge from the anus of the host at night, lay about 20,000 eggs on the perianal skin, and then die. The eggs, which embryonate within four hours of exposure to air, cause anal pruritus that leads to scratching and to the deposition of eggs under the fingernails of the already parasitized host. 3 The lifespan of