Natural History.—The ascaris vermicularis, or small threadworm, has its habitat in the rectum, though it is sometimes found higher in the bowel, and occasionally in the vagina in the female.
The head is subulate, and divided into three vesicles, in the middle of which it receives nourishment; skin at the sides of the body finely crenate or wrinkled; tail finely tapering and terminating in a point; gregarious, viviparous, and about half an inch long.
Symptoms.—The ascaris vermicularis makes itself known by an intolerable itching and crawling sensation about the anus. At first it generally comes on after the little patient gets warm in bed, the irritation being so great that sleep is impossible; at last, they are more or less troublesome all the time. The irritation is occasionally so great as to impair the health, and occasionally gives rise to convulsions.
"The worm is occasionally found wandering outside to the sexual organs, which, from the itching caused, sometimes leads to masturbation in children.
They are readily detected in the feces. Infection probably takes place through the water, or possibly through salads, such as lettuce and cresses. A person, the subject of the worms, passes ova in large numbers in the feces, and the possibility of reinfection must be scrupulously guarded against.
Treatment.—Many remedies have been recommended for the ascaris vermicularis, but it is very questionable whether vermifuge medicines have any effect upon the parasite. Its local habitat being the rectum and lower portion of the colon, all that will be necessary for their removal is an injection of strong salt water. A strong decoction of quassia is also attended with good results.
Having thoroughly cleared the bowel of the irritating parasite, the tonicity of the bowel must be improved. Nux vomica, sulphur, and such agents as will secure a normal peristaltic action of the intestine, should be administered.