The practice of pediatrics . s(Figs. 60, 61 and 62). 3. Strongyloides, ankylostomum duodenale(Figs. 63, 64, 65 and C6). INTESTINAL PARASITES 311 Taeniae or Tape-worm. Modes of Infection.—Each of these teniaepasses through a life cycle of three stages: 1. The egg. 2. The embryoor larva. 3. The mature worm. The full-grown parasites are foundonly in the intestinal canal of man. Eggs are passed from any of thesegments of the worm, mingle with the feces, and are passed from thehost. For its further development the egg must he taken into thealimentary tract of another animal. Thus the egg of the ten
The practice of pediatrics . s(Figs. 60, 61 and 62). 3. Strongyloides, ankylostomum duodenale(Figs. 63, 64, 65 and C6). INTESTINAL PARASITES 311 Taeniae or Tape-worm. Modes of Infection.—Each of these teniaepasses through a life cycle of three stages: 1. The egg. 2. The embryoor larva. 3. The mature worm. The full-grown parasites are foundonly in the intestinal canal of man. Eggs are passed from any of thesegments of the worm, mingle with the feces, and are passed from thehost. For its further development the egg must he taken into thealimentary tract of another animal. Thus the egg of the tenia soliumfinds its refuge in the intestine of the hog. There the capsule of theegg is dissolved, the egg develops into an embryo which passes throughthe intestinal wall into the muscles of the host, by virtue of certainsmall, hook-like processes on the head, and then becomes encysted. Ananimal whose muscles are full of these encysted larva? is spoken of asmeasly or measled. The larvae remain in this state until the Fig. 56. i j pi jiiiit 1. Head of tenia solium; magnification, 50; 2, 3,mature and semimature segments, natural size;4, two proglottides with uterus, twice magnified. (From Ziegler, after Leuckart.) flesh of the host is consumed as meat by man, when they are set freein the intestine, where they develop into mature worms and their lifecycle is complete. For the tenia saginata cattle are the intermediatehosts; for the bothriocephalic latus fish. It is possible that man himself, taking the ova of any of these wormsinto the stomach, may become the intermediary host—, lodge thelarval form. This is known to happen in the case of taenia solium, theencysted larva? of which, the cysticercus cellulosa?, are sometimes foundin human muscle, the brain, etc. Taenia Saginata or Mcdiocanellata.—This is the most common tape-worm in Europe and this country. Infection occurs through eatingmeasly beef. The length of the parasite varies from 4 to S metres 312 DISEASES OF THE AL
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