THE ECHINOCOCCUS The Tmnia echinococcus (Fig. 57) is a broad tapeworm, .2 or .3 mm. wide; and reaching a length of, at most, 5 mm. It is often found in enormous numbers in the intestine of the dog and other animals, such as wolves, jackals, and foxes. Microscopically, the head is armed with a claw-like rostellurn and four suckers. Of the three proglottides, the last one contains from four hundred to five hundred eggs, which have a diameter of .02 mm., and contain an embryo with hooklets.
When the eggs reach the gastro-intestinal canal of man or other omnivorous or herbivorous animals, the embryo becomes free; and, partly actively and partly passively, through the blood and the lymph-stream, reaches the different organs of the body—and most frequently, the liver.
There develops gradually from the embryo a cyst filled with fluid, the acephalocyst. Slowly this becomes larger. A cuticle several layers thick develops; also an intercellular parenchymatous layer. The organ affected produces itself a connective-tissue capsule around the cyst (Fig. .58). Small capsules are formed within the cyst, by the proliferation of the parenchymatous layer, from whose inner wall pedunculated heads spring, having a circle of hooks and four suckers. The whole picture represents the measled stage of the above-described echinococcus tapeworm. and is called for brevity echinoeoccus.
1. In the above-described form, We have the Echenococcus simplex. Then similarly constructed formations develop from the wall of the mother-eyst (acephalocy-st), which are called daughter-cysts. On the parenchymatous layer of these, we find the formation of breeding-cham bers with heads. -We may- find the formation of granddaughter-cysts from the daughter-cysts.
2. This form is called the Bchittococcus composites hydatidosus (E. eompositus endogenus). It is the most frequent forni of echinococcus found in man. Since the proliferation of the parenchymatous layer occurs within the cyst, these two forms are also designated echinococcus endogenus (Fig. 5tii; but when the proliferation of the parenchymatous layer breaks through the cuticular layer externally, and the (laughter or granddaughter-cysts become situated outside the mother cuticle, then there results: 3. The Eehinocoectts ectogenue, or granulosus, which is found in man in the omentum, the peritoneum, etc. (Fig. 59).
4. A sub-variety of the latter is the Echinococcus multilocularis, which represents a group of very small, closely packed cysts, and may reach the size of a human fist. In sections of the
same (Fig. 60) one sees nothing but small cavi ties with jelly-like con tents, containing the heads and sconces. The echinococcus multiloc ularis seems to arise from continued budding, and is often found in the liver of man.
All four varieties of eehinococcus are derived from the tamia echinococcus of the dog.
-Within the eclainococcus bladder, we find a clear, slightly( opales cent fluid, with a specific gravity of 1.009 to 1.015. This contains traces of albumin, sugar, inosit, leucin, tyrosin, cholesterin, hematoidin, and succittic acid, together with the sodium and calcium salts of the latter. Out of 1.5 per cent. of inorganic substance, .5 to .S per cent. are sodium chloride. Brieger found present a substance with poisonous properties.
Symptoms.—In regard to the symptornatology of the echinococcus in man, I can speak only( from a general standpoint. Since the echino coccus is found sometimes singly and sometimes with several species in one or several organs of the body, its action may be manifold. This Is evident from its size and the conditions of its life, as well as from the effect on the function of the organs affected. The ernbry-o, which wanders in, sets up first local irritation, which the organ affected meets by en closing it in connective tissue. This encapsulation does not occur in cavities. The growth of the acephalocyst is very slow for several months. The increase in size canses, at first, no difficulty for the host. It is painless, but when a certain size has been reached pressure symptoms arise. After further growth, these symptoms are not confined to the organ affected, but extend to the neighboring parts of the body. The echinococci enter the adjoining parts of the body either spontaneously Or as the result of trauma. They frequently enter the cavities of the body; and the resulting absorption of echinococcus fluid results in repeated attacks of hives and severe, even fatal, intoxi cation. The parasite can exist in some organs for years, without affecting its host. On the other hand, it may unsuspectecily lead to sudden death, or sed up a chronic marastmis. The eehinococcus may die, and become encapsulated; it may also spreacl, and lead to fatal pytternia. The case-reports on echinococcus disease are unusually plentiful.