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Enterobius vermicularis, Molecular Detection

Molecular testing for Enterobius vermicularis (pinworms) is used for the diagnosis and laboratory documentation of enterobiasis.

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Enterobius vermicularis (pinworms) is one of the most common human parasitic helminths and by one estimation, about 200 million people worldwide are supposedly infected, with children aged 5 -10 years old accounting for over 30% of cases.

Regardless of one’s particular socioeconomic level, race, or culture, pinworm infection can be facilitated by certain factors such as poor personal or group hygiene, and overcrowding in preschools, schools, orphanages, and family groupings. These conditions favor pinworm eggs transmission from person to person, directly via the anus-to-mouth route and finger contamination or indirectly by contaminated objects, e.g., toys, classroom tables, chairs, or the ground. Since personal hygiene and exposure are important transmission factors, preschool-aged children who live in crowded environments such as kindergartens are the most common group susceptible to pinworm infection

Human pinworm (Enterobius vermicularis) is a white nematode parasite. It reaches the size of approx. 1 cm (females) or approx. 3 mm (males). Human pinworm parasitizes only in the human body, in the large intestine, the appendix, and the terminal section of the small intestine. It feeds on substances present in the intestinal contents. Females live about 4 weeks, and males die immediately after breeding. The female lays 8000-12000 eggs containing parasite larvae. Within 4-8 hours, the larvae achieve invasive ability.

Pinworm causes a disease called enterobiasis. The course of enterobiasis depends on the number of parasites and the host’s immunity.

Enterobiasis is frequently asymptomatic. The most typical symptom is perianal pruritus, especially at night, which may lead to excoriations and bacterial superinfection. Occasionally, invasion of the female genital tract with vulvovaginitis and pelvic or peritoneal granulomas can occur. Other symptoms include teeth grinding, enuresis, insomnia, anorexia, irritability, and abdominal pain, which can mimic appendicitis. E. vermicularis larvae are often found within the appendix on appendectomy, but the role of this nematode in appendicitis remains controversial. Very rare instances of eosinophilic colitis associated with E. vermicularis larvae have been reported.

Sick children do not sleep well due to severe itching in the anal area. Enterobiasis causes also abdominal pain, defecation disorder, nausea, dermatitis, and rash.

The appropriate diagnostic specimen is a perianal swab for screening instead of stool examinations since eggs can be detected in only about 5% of fecal samples.

 

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