pinworm

pinworm,

roundworm, Enterobius vermicularis, worldwide in distribution and the most common source of worm infestation of humans in the United States. Children are more commonly infested than adults. Adult pinworms inhabit and mate in the cecum of the large intestine and adjacent areas. When mature females become gravid they migrate down the colon and out onto the skin around the anus where they lay about 10,000 eggs and then die. Such movements cause intense anal itching. The eggs are infective within a few hours and are easily spread by the hands to the mouth, most often through touching contaminated household objects or food supplies. If infective eggs are swallowed the young worms hatch in the duodenum and migrate to the cecum. Development from ingested egg to gravid female requires 2 months. The most prominent symptom of the disease resulting from pinworm infestation, called enterobiasis, is anal itching, particularly at night; restlessness and insomnia are common, and sometimes gastrointestinal symptoms such as abdominal pain, nausea, and diarrhea, are also present. Since reinfection is a major problem, enterobiasis is treated by the following of strict hygienic measures, including careful cleansing of hands, body, and bed linens. Often, all members of the household must be treated for the disease. Pinworms are classified in the phylum Nematoda, order Oxyuroidea, family Oxyuridae.

Pinworm

 

(Enterobius vermicularis), a roundworm of the suborder Oxyurata that parasitizes humans. The cuticle forms a swelling, or vesicle, near the head. The mouth is surrounded by three lips and opens into the esophagus, which is enlarged toward the end. The female is 9–12 mm long and has a narrow posterior end. The male measures 2–5 mm in length; the posterior part of the body ends bluntly and is greatly bent. The colorless eggs are about 0.05 mm long.

Pinworms live in the terminal part of the small intestine and throughout the large intestine. Mature females migrate outside the anus and, after depositing their eggs (about 12,000), they die. A person becomes infected by swallowing the eggs. Itching occurs as the pinworm leaves the body and deposits its eggs. Severe infestation may cause nervous and gastrointestinal disorders. A rash may develop near the perineum. Children may experience nightmares, engage in masturbation, and contract leukorrhea. The disease caused by pinworms, enterobiasis, is prolonged because of auto-infection (the life span of a pinworm is about one month).

REFERENCE

Vasil’kova, Z. G. Osnovnye gel’mintozy cheloveka i bor’ba s nimi, 2nd ed. Moscow, 1953.

B. E. BYKHOVSKII

pinworm

[′pin‚wərm]

(invertebrate zoology)

Enterobius vermicularis. A phasmid nematode of the superfamily Oxyuroidea; causes enterobiasis. Also known as human threadworm; seatworm.