Milford Daily News
  • Hersh: Are pinworms common in children?

  • Q: My daughter’s school called to say there is an outbreak of pinworms in her class from one of her preschool classmates. Is this still a common thing for kids to get?

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    A: Pinworm is a helminthic infection caused by Enterobius vermicularis. To understand the infection, we need to follow this parasite through its life cycle.
    The E. vermicularis eggs are ingested after someone touches a contaminated object, person (the person is not infectious per se, but if they have not washed their hands well they can have some of the eggs underneath their fingernails or on their hands) or themselves (called autoinfection where the patient re-infects themself) and then touches their mouth or food. Over the course of a month or so, a few to several hundred eggs hatch into larvae in the intestines and grow to adulthood (females are a quarter to half inch long, males about a quarter that size) where they can live for a couple of months in the lower large intestines. The female worms migrate to the anus, usually at night, where they can lay up to 10,000 eggs. Some of the eggs can then leave the host’s body, contaminate an object, the host’s hands, etc., and if ingested by the patient or another person the cycle recurs. Once on an object the eggs can live a couple of days if there are dry, warm conditions, or up to a couple of weeks in cooler, moister conditions.
    Up to 40 million or more Americans are infected with pinworms, with infection being more common in children and those living in close quarters (such as institutionalized people or others living in crowded conditions). Pinworm infections are also more common in cities (closer quarters), especially those in cool temperate climates (the eggs can survive longer).
    Most of the people infected with pinworms have no symptoms. However, when people do get symptoms the most common is pruritus (itch by their rectum) due to movement of the worms or movement/irritation from the eggs. Rarely, there are other complications of pinworm infection, including weight loss or spread of the infection (and symptoms such as itch) to other locations (for example to a female’s reproductive organs). There have also been studies published suggesting an increased risk of appendicitis in patients with pinworm infections.
    The diagnosis of pinworm is made by identifying the worms or the eggs in the infected individual. This can be done by using cellophane tape to gather a sample from the patient’s rectum and examining it under a microscope to look for the eggs or even the quarter- to half-inch-long adult female worms. Since there will not always be eggs or worms present, this testing should be repeated up to three separate times, and is typically done in the morning (the pinworms are typically active overnight so are more likely to be found the first thing in the morning).
    Page 2 of 2 - Certain medications are active against worms, and can eradicate a pinworm infection. Since there can be eggs by the anus and autoinfection is common, it is often necessary to give a second dose of these medicines a couple of weeks after the first dose to minimize recurrence of the infection. When there is concern that many people are infected (such as if an entire family is infected or when there is a widespread infection within a close living situation), everyone should be treated simultaneously to prevent the infection from "bouncing" back and forth among the group.
    Preventing the spread of pinworm infection, especially in high-risk situations such as close living quarters, relies on proper hygiene, specifically including thorough hand washing prior to eating. Infected patients should clean their bedding (and for children toys and other things they commonly touch and/or put in their mouths) with soap and hot water every couple of days, and underwear and pajamas should be changed and washed daily.

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