ANIMAL PARASITES a few years ago, wornis played an important r6le in the pathology of childhood, both with physicians and the laity. The chief reason for this was the deficient know-ledge, not only of many children's diseases, but also of the life conditions of these parasites. The thorough study of the latter has now completely cleared up a series of biological questions; and now, since more light has been thrown upon many obscure problems in children's diseases, a great many physicians are inclined to minimize the importanee of helminthiasis in the causation of disease. The fact that in the majority of eases certain parasites eall forth few or very vague symptoms when present only s.ingly or in small number must be opposed by the other consideration that certain of our parasites are always dangerous guests, and that at times even "harmless" worms ean cause serious conditions. With regard to the effect of animal parasites on their host, we must w-eigh the following.
1. They withdraw albumin from their host.—liven if this is not of much moment, as a rule, it may, nevertheless, be of importance when we have to do with a tender, youthful, and armernie organism. Accord ing to Leuckart, the tainia saginata throws off, in the course of a year, five hundred and fifty grains of proglotticles. The female asearis produces, sometimes, forty grams of eggs in the same time. These losses in albumin, which are not essentially great, niay beeome very much greater when a large number of parasites are present. The ankylostomuna duodenale eauses much more serious disturbance, since it sticks blood and can give rise to seeondary hirmorrhages from the wounds it makes. Quite severe, and even fatal anaania, may be brought about by these parasites.
2. Their entrance, as well as their occasional wanderings through the body, way bring about a series of injuries.— In this regard we must
mention myositis from trichime and eystieerci, meningitis from cysti cerci, liver-abscess from annteboe and thread-worms, and fatal asphyxia due to the wanderings of the latter into the larynx and bronchial tubes.
3. They act as foreign bodies.—Conglornerations of round-worms have eaused intestinal stenosis with fatal results. The cysticerci and eehinococci also produce many pressure symptoms and invasion symptoms, according to their size and location.
4. They act through their products of metabolism, on the blood and the (nervous system of their host. — latter years, the presence of blood and nerve poisons in human and animal parasites, have been demon strated by a series of experiments. The poisonous action of echinocoecus fluid has long been known. The symptomatology, diagnosis, and thera peutics of these conditions will be considered with the respective parasites.
In general, it must be emphasized that the physician should never be persuaded by the vague statements or suppositions of the parents to treat a child for worms; for those in eharge often suppose that a child has worms. On the other hand, they may be easily deceived by the passoge of matter resembling links, which has often been deseribed literature under the name of pseudohelminthiasis. An exact diagnosis is possible for most of our parasites. Only then must We order vermi fuges, beginning with the milder remedies and passing to the stronger; if necessary, repeating the cure once or several times. In each case, certain questions must be taken into consideration. The following chapter will give a short resume. of that which is worth knowing in parasitology by the practitioner ancl the student.