The gravid female migrates to the anus and deposits eggs in the perianal skin folds usually at nighttime. The movement of the female and the ova cause intense local pruritus. Ova may survive for up to 3 weeks before hatching. The larvae can then migrate back into the anus and lower intestine causing retroinfection. Overall, males are affected twice as often as females are except in ages 5-14 years, when females predominate.
Most patients are asymptomatic.
The most common complaint is anal pruritus, usually nocturnal or in the early morning. Perianal excoriations secondary to scratching may be found. Glass slide microscopic analysis may be performed to look for ova and females. A specimen is best obtained by dabbing the stretched, unwashed perianal folds in the early morning with cellophane tape and affixing on to a slide. A negative test for 5 consecutive mornings effectively rules out the diagnosis.