Enterobiasis is an intestinal infestation by the pinworm Enterobius vermicularis , usually in children. Its major symptom is perianal itching. Diagnosis is by visual inspection for threadlike worms in the perianal area or the cellophane tape test for ova. Treatment is with mebendazole , pyrantel pamoate , or albendazole. See also Approach to Parasitic Infections.
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Another putative pinworm species, Enterobius gregorii , has been described and reported from humans in Europe, Africa, and Asia. However, further morphologic and molecular evidence suggests E. The rat pinworm, Syphacia obvelata , has also very rarely been reported infecting humans. Gravid adult female Enterobius vermicularis deposit eggs on perianal folds.
Infection occurs via self-inoculation transferring eggs to the mouth with hands that have scratched the perianal area or through exposure to eggs in the environment e. Following ingestion of infective eggs, the larvae hatch in the small intestine and the adults establish themselves in the colon, usually in the cecum.
The time interval from ingestion of infective eggs to oviposition by the adult females is about one month. At full maturity adult females measure 8 to 13 mm, and adult males 2 to 5 mm; the adult life span is about two months. Gravid females migrate nocturnally outside the anus and oviposit while crawling on the skin of the perianal area.
The larvae contained inside the eggs develop the eggs become infective in 4 to 6 hours under optimal conditions. Rarely, eggs may become airborne and be inhaled and swallowed.
Retroinfection, or the migration of newly hatched larvae from the anal skin back into the rectum, may occur but the frequency with which this happens is unknown.
Oxyurid nematodes pinworms generally exhibit high host specificity. Humans are considered the only host for E. 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, enuresia, insomnia, anorexia, irritability, and abdominal pain, which can mimic appendicitis.
Very rare instances of eosinophilic colitis associated with E. They are transparent, elongate to oval in shape, and slightly flattened on one side. They are usually partially embryonated when shed. Eggs will adhere to the tape and can be seen microscopically.
Adult males of Enterobius vermicularis measure up to 2. Adult males have a blunt posterior end with a single spicule; females possess a long pointed tail. In both sexes, there are cephalic expansions. Microscopic identification of eggs collected in the perianal area is the method of choice for diagnosing enterobiasis. Eggs can also be found, but less frequently, in the stool, and occasionally are encountered in the urine or vaginal smears.
Adult worms are also diagnostic, when found in the perianal area, or during anorectal or vaginal examinations. In cases of ectopic infection, eggs may be seen in the urine or in cervicovaginal Papanicolaou smears. More on: Morphologic comparison with other intestinal parasites. Standard precautions apply for processing stool samples also tape test samples to avoid accidental ingestion of infectious eggs.
Surfaces should be cleaned thoroughly as the outer coat of E. Peixoto, A. Eosinophilic ileocolitis due to Enterobius vermicularis infection: a rare cause of anemia. International Journal of Colorectal Disease , 31 3 , pp. Hasegawa, H. Is Enterobius gregorii Hugot, Nematoda: Oxyuridae a distinct species? The Journal of parasitology 84, pp. DPDx is an educational resource designed for health professionals and laboratory scientists.
For an overview including prevention, control, and treatment visit www. Skip directly to site content Skip directly to page options Skip directly to A-Z link. Section Navigation. Minus Related Pages. Life Cycle View Larger. Enterobius vermicularis eggs. Figure A: Eggs of E. Figure B: Eggs of E. Figure C: Egg of E. Figure D: Egg of E. Figure E: Eggs of E. Figure F: Eggs of E. Enterobius vermicularis adult worms. Figure A: Adult male of E. The worm measured 1. Figure B: Close-up of the anterior end of the worm in Figure A.
The esophagus, divided into muscular and bulbous portions and separated by a short, narrow isthmus, is visible in the image, as are the cephalic expansions. Figure C: Close-up of the posterior end of the worm in Figure A. Note the blunt end.
The spicule is withdrawn into the worm in this specimen. Figure D: Adult female E. Figure E: Male and female E. Figure F: Posterior end of an E. Figure A: Cross-section of a male E. Notice the presence of the alae blue arrow , intestine red arrow and testis black arrow.
Figure B: Cross-section of an adult female E. Note the presence of the alae blue arrow , intestine green arrow and ovaries black arrows.
Figure C: Cross section of an adult female E. Note the prominent alae blue arrow and the presence of eggs yellow arrow. Image contributed by Sheboygan Memorial Hospital, Wisconsin.
Figure D: Longitudinal section of an adult female E. Note the presence of many eggs. Figure E: Egg of E. Figure F: Egg of E. Laboratory Diagnosis Microscopic identification of eggs collected in the perianal area is the method of choice for diagnosing enterobiasis. Laboratory Safety Standard precautions apply for processing stool samples also tape test samples to avoid accidental ingestion of infectious eggs. Suggested Reading Peixoto, A. Cook, G. Enterobius vermicularis infection. To receive email updates about this page, enter your email address: Email Address.
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Pinworm infection , also known as enterobiasis , is a human parasitic disease caused by the pinworm. The disease is spread between people by pinworm eggs. Treatment is typically with two doses of the medications mebendazole , pyrantel pamoate , or albendazole two weeks apart. Pinworm infections commonly occur in all parts of the world. One-third of individuals with pinworm infection are totally asymptomatic.
Another putative pinworm species, Enterobius gregorii , has been described and reported from humans in Europe, Africa, and Asia. However, further morphologic and molecular evidence suggests E. The rat pinworm, Syphacia obvelata , has also very rarely been reported infecting humans. Gravid adult female Enterobius vermicularis deposit eggs on perianal folds. Infection occurs via self-inoculation transferring eggs to the mouth with hands that have scratched the perianal area or through exposure to eggs in the environment e.