Common name. pinworm, seat worm

Disease. enterobiasis

Geographic distribution. cosmopolitan in cool and temperate zone.

Life cycle. Human is the only known host of E. vermicularis. The usual habitat is the colon. Pinworm infection in human is initiated by the ingestion of the infective eggs, which hatch in the intestine, where they develop into the adult worms. In gravid females, almost of the entire body is filled with the eggs. The female worms migrate down to the colon and out of the anus, where the eggs are deposited on the perianal and perineal skin. Occasionally, the female worm migrates into the vagina.

Morphology. The female worm measures 8 to 13 mm long and has a pointed tail (hence the common name "pinworm"). The male worm is inconspicuous, about 2～5 mm long. The eggs are oval, compressed laterally, and flattened on one side and measure 50 to 60 ㎛ long by 20 to 30 ㎛ wide.

Pathology and clinical symtoms. Many cases of E. vermicularis infection are asymptomatic. The most striking symptom of this infection is pruritus, which is caused by the migration of the female worms from the anus onto the perianal skin.

Diagnosis. Diagnosis is normally accomplished by sampling the perianal and perineal skin with cellulose addhesive tape. It is important to note that multiple samples may be required to confirm the presence of a light infections as well as to conclude that a patient is free of infection.

Treatment. The treatment of choice for the enterabiasis is mebendazole and albendazole. It should be repeated 2 weeks later. All of the family members should be treated together at the same time.

Prevention. Proper personal hygiene: hand washing, applying ointment, perianal area to avoid dispersal..

Eggs of E. vermicularis (x400) --from 6-year boy.
Cellophane-tape impression showing pinworm ova.

Eggs of E. vermicularis (x400) --from 6-year boy.
Cellophane-tape impression showing pinworm ova.

Eggs of E. vermicularis (x400) --from 6-year boy.
Cellophane-tape impression showing pinworm ova.

The embryonated ggs of Enterobius vermicularis.

E. vermicularis (male adult) xl00

E. vermicularis adult(female) showing esophageal bulb. x200

Anterior part of E. vermicularis (female) showing cephalic alae. x200

Anterior and posterior parts of female Enterobius vermicularis.

A cross section of female Enterobius vermicularis at midgut level shows lateral alae, intestine and intra-uterine eggs. H & E stained. x200.

A section of Enterobius vermicularis found in the appendix.

A longitudinal section of female Enterobius vermicularis in the cecum. H & E stained. x100.

A longitudinal section of female Enterobius vermicularis in the cecum. H & E stained. x200.