Thread-Worms, a name applied to the small, cylindrical worms which form the class of Nematoda. The Common Thread-worm (Oxyurus vermicularis) is a Nematode worm [ROUND WORM], and is one of the most common of the parasites which infest the human intestine. The female is rather less than 1/2 inch long, the male about half this size; the eggs are oval bodies of about 1/500 of an inch in length in the long diameter. Thread-worms are more common in children than in adults; they inhabit the lower bowel, and usually give rise to itching about the anus. The fact of their presence is readily verified by the detection of the worms themselves or of their ova in the faeces. The local injection of quassia, combined, if necessary, with the use of parasiticide ointments, is usually effectual in destroying the worms.