Background
Pinworm, or Enterobius vermicularis, is prevalent throughout the temperate regions of the world and is the most common helminthic infection in the United States.
E vermicularis is a white slender nematode with a pointed tail. In humans, they reside in the caecum, appendix, and ascending colon. Female pinworms (8-13 mm long) are larger than their male counterparts (2-5 mm long). Pinworm infection is generally asymptomatic; however, some infected individuals experience sharp prickling pains or intense itching in the anal area, especially at night.
Pinworm. Adult female worms of Enterobius vermicularis collected from a 2-year-old girl in a Korean orphanage after treatment with pyrantel pamoate 10 mg/kg, November 24, 1975. Pinworm infection is primarily a pediatric condition. Parents are typically infected via transmission through their children.
Transmission can occur via direct contact with contaminated furniture, bedclothes, bedding, towels, toilets, doorknobs, or other objects. The parasite can also be transmitted during sexual contact.
Pathophysiology
Pinworms that inhabit the caecum and adjacent areas typically cause no symptoms. Diarrhea due to inflammation of the bowel wall can occur during acute infection.
The primary symptoms of pinworm infection, which include pruritus or a prickling sensation in the perianal area, are produced when a gravid female pinworm migrates to the anal area and inserts her tail pin into the mucosa for ovideposition.
Although pinworms have been found in the region of the appendix during histologic studies of acute appendicitis, the relationship is most likely incidental.[1]
Epidemiology
Frequency
United States
Pinworm infection is most common in persons who live in crowded living conditions and in individuals who are institutionalized. The general prevalence of pinworm infection in some regions may be as high as 12%.
International
Pinworm infection is most common in cosmopolitan areas in cool and temperate regions. Egg carrier rates vary by country, from 0.1-98.4%.
Mortality/Morbidity
Pinworm infection does not cause severe morbidity unless ectopic infection occurs. This rare complication occurs in individuals with conditions that compromise the integrity of the bowel wall (eg, inflammatory bowel disease). Parasites migrate through the bowel wall and are found in extracolonic sites. Ectopic enterobiases have been described in various locations, including the vagina, salpinx, inguinal area, genital area, pelvic peritoneum, omentum, liver, salivary glands, male genital tract, and even the lungs. They have also been associated with acute appendicitis, eosinophilic colitis, and eosinophilic gastroenteritis.[2]
Race
Pinworm infection has no reported racial predilection.
Sex
Pinworm infection has no sexual predilection.
Age
- Of all age groups, school-aged children are most at risk for pinworm infections.
- In adults, pinworm infection is most common in parents aged 30-39 years, typically because of transmission from their children aged 5-9 years.
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