Pinworm
From Freepedia
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| Image:Threadworm.jpg Two pinworms, captured on emergence from the anus. Markings are 1mm apart | ||||||||||||
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The pinworm (Genus Enterobius) is a parasitic roundworm of the phylum Nematoda. The best known is the human pinworm, also known as the threadworm Enterobius vermicularis. It is found worldwide and causes the common infection enterobiasis in humans. The adult pinworm male is 1–4 mm in length, while the adult female is 8–13 mm and possess the long, pin-shaped posterior end for which the worm is named.
The pinworm lives in the lower part of the small intestine, and the upper part of the colon. After mating the male dies. The female migrates to the anus, and emerges (usually during the night) to deposit 10000 to 20000 eggs in the perianal area (around the anus). It secretes a substance that causes a very strong itching sensation, inciting the host to scratch the area and thus transfer some of the eggs to the fingers. Once ingested orally, the larvae hatch and grow to maturity in 30-45 days.
Unlike many other intestinal parasites, the pinworm does not usually enter the bloodstream or any other organs besides the intestines. Only in rare cases disoriented pinworms can be found in the vagina, and even more rarely in the uterus, fallopian tubes, liver and peritoneum; but the worms cannot survive long in these places. Except for the itching, it does not usually cause any damage to the body. Sleep disturbance may arise from the itching or crawling sensations. Diagnosis is usually made clinically by observing the female worm (or many worms) in the peri-anal region, but can also be made using the "scotch-tape" test. Clear tape is used to lift a sample off the anal region and then sent to a lab to look for eggs. Pinworm infestation is treated using mebendazole, a spindle poison that induces chromosome nondisjunction. Treating the entire family is often necessary for cure.
