The disorder occasioned by these worms frequently becomes an epidemic in years of heavy rain, and especially in marshy districts. It appears also to be connected with the season, being especially prevalent iu the East Indies during the rainy season, and in Upper Egypt shortly after the regular inundation of the Nile.
The mode of production of this parasite in the human body is not known with cer tainty. The probability is, that the young animals, while still very minute, penetrate the skin, although by what mechanism they can effect their lodgment, we do not know. Carter relates a case which strongly supports this view. Fifty children in a school at Bombay went to ltathe in a pond. and 21 of them were attacked by the Gninen-wmtn; sonic of them having four or five worms. Moreover. it is well known that negroes who are in the habit of entering the water more frequently than the whites, and generally have their feet naked, are far more liable to be at tacked than Europeans. The part of the hotly in which the worm usually manifests itself also accords with this view. )'Gregor states that, in 172 cases, it occurred 124 times in the feet, 33. times in the legs, 11 times in the thighs, twice in the hands, and twice elsewhere.
Having gained an entrance into, the body, the Guinea-worm takes a considerable time to be developed. This perida varies from two Months to' a year or even two years. Tho presence of the worm often produces no annoyance for a considerable time after it has been detected; at other times, it gives rise to emaciation, and possibly even death from exhaustion. As a genernl rule, the vesicles caused by the inflammation excited In' the
presence of the worm open spontaneously in a few days, and two or three inches or the anterior end of the animal come forth. This end is gently pulled, and coiled round a little roll of linen or a small stick, and this is fastened over the wound with sticking, plaster and a compress. The extraction is repeated twice a day by rotating time substance round which the worm is twisted, and the Operation is often not completed in less than two. three, or more months. From the most ancient times, the tearing of the worm has been regarded as a very dangerous accident. It undoubtedly gives meta violent swel hng, fever, and sleeplessness; and if we are to trust. the statements of some of the older observers, shortening and deformities of the legs, lingering fistula, mortification, and death (sometimes even sudden death) must be reckoned amongst the probable conse quences of breaking the worm.
Although the ordinary seat of this worm is the subcutaneous cellular tissue, it has been found in the tongue, in the layers of the mesentery behind the liver, and under the conjunctiva of the eye. Small filarke of a different species have occasionally been found iu the lens of human eye.