Monday, November 20, 2017

Enterobius Vermicularis Infection in Children



ETIOLOGY.
The cause of enterobiasis, or pinworm infection, is Enterobius vermicularis,which is a small (1 cm in length), white, threadlike nematode, or roundworm, that typically inhabits the cecum, appendix, and adjacent areas of the ileum and ascending colon. Gravid females migrate at night to the perianal and perineal regions, where they deposit up to 15,000 eggs.Eggs embryonate within 6 hr and remain viable for 20 days.

MODE OF INFECTION.
Human infection occurs by the fecal-oral route typically by ingestion of embryonated eggs that are carried on fingernails, clothing, bedding, or house dust. After ingestion, the larvae mature to form adult worms in 36–53 days.

PATHOGENESIS.
Enterobius infection may cause symptoms by mechanical stimulation and irritation, allergic reactions, and migration of the worms to anatomic sites where they become pathogenic.

CLINICAL MANIFESTATIONS.
Pinworm infection is innocuous and rarely causes serious medical problems. The most common complaints include itching and restless sleep secondary to nocturnal perianal or perineal pruritus. The precise cause and incidence of pruritus are unknown. They may be related to the intensity of infection, psychologic profile of the infected individual and his or her family, or allergic reactions to the parasite.


Aberrant migration to ectopic sites occasionally may lead to appendicitis, chronic salpingitis, pelvic inflammatory disease, peritonitis, hepatitis, and ulcerative lesions in the large or small bowel.

DIAGNOSIS.
A history of nocturnal perianal pruritus in children strongly suggests enterobiasis. Definitive diagnosis is established by identification of parasite eggs or worms. Microscopic examination of adhesive cellophane tape pressed against the perianal region early in the morning frequently demonstrates eggs . Repeated examinations increase the chance of detecting ova.

TREATMENT.
Anthelmintic drugs should be administered to infected individuals and their family members.

A single oral dose of mebendazole (100 mg PO for all ages) repeated in 2 wk results in cure rates of 90–100%. Alternative regimens include a single oral dose of albendazole (400 mg PO for all ages) repeated in 2 wk or a single dose of pyrantel pamoate (11 mg/kg PO, maximum 1 g).

Morning bathing removes a large portion of eggs. Frequent changing of underclothes, bed clothes, and bed sheets decreases environmental egg contamination and may decrease the risk for autoinfection

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