Pinworm (Enterobius vermicularis) infections are the most common worm infection in America. Although any individual may develop a case of pinworms, the infection occurs most frequently in school children between 5 to 10 years of age. Pinworm infections occur in all socioeconomic groups; however, human-to-human spread is favored by close, crowded living conditions. Spread among family members is common. Animals do not harbor pinworms - humans are the only natural host for this parasite.
The most common symptom of pinworms is an itchy rectal area. Symptoms are worse at night when the female worms are most active and crawl out of the anus to deposit their eggs. Although pinworm infections can be annoying, they rarely cause serious health problems and are usually not dangerous. Therapy with routine prescription medications provides an effective cure in almost all cases.
The very simple life cycle of E. vermicularis ensures a high human prevalence. Tiny eggs deposited around the anus by a female worm spread the infection. Each female worm can produce more than 10,000 eggs during her lifespan. When someone with pinworms scratches their perianal area, eggs may lodge under their fingernails and be spread to anything he or she touches. Infested dust, clothing, bedding, or toys can also spread eggs. When someone else accidentally ingests these eggs, they also become infected.
Over the next several weeks, newly ingested eggs hatch and mature into adult worms. The new worms migrate to the junction between the small and large intestine. Following further maturation, the newly "pregnant" worm migrates from this region to the rectum. From here she will make the trip to the anal area (commonly at night) and deposit her eggs. The life cycle has now come full circle. Adult females live for approximately three months in their human host. Their eggs may die within one to two days in a warm and dry environment; however cool and humid conditions will allow their survival for up to two weeks.
Medically Reviewed by a Doctor on 6/19/2015
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