The inspection of meats for animal parasites / prepared under the direction of D.E. Salmon.

Date:
1898
Catalogue details

Licence: Public Domain Mark

Credit: The inspection of meats for animal parasites / prepared under the direction of D.E. Salmon. Source: Wellcome Collection.

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    Tasckenberg (1889, pp. 1036-1057); (1877-1890) Huber (1891. pp. 5-39); also Billings, Index Cat. Lib. Surg. Gens. Office, United States Army, 1885, VI, pp. 530-535. Hosts.—Man, cattle, sheep, swine, and other animals. (See pp. 137-143.) Adult stage (Taenia echinococcus Siebold, 1853). For anatomical characters, compare figs, 102-104 with key, p. 101. Synonymy.—“Taenia caieniformi8,i misdet. pro parte Rudolphi, 1808; “T. cucu- merina Bloch” misdet. pro parte, Diesing, 1850; “T. serrata” misdet. Roll, 1852; T. echinococcus Siebold, (1853); T. nana Beneden, 1858 [nec Siebold, 1852]; Echinococci/cr echinococcus (Siebold) Weinland, 1858; “T. ecliinococca” of Koeberld, 1861; T. (Echino- coccifer) echinococcus of Leuckart, 1863; T. (Arhynchotaenia) echinococcus of Diesing, 1864; T. (Echinococcus) echinococcus of Railliet, 1886; T. “ echinokokkm” of Schneide- miihl, 1896. Hosts.—Dog, dingo, jackal, wolf, cougar (?). (See pp. 137-143.) Life history.—Starting with the adult tapeworm (fig. 103) in the small intestine of the dog or wolf, the eggs are scattered over the ground and are swallowed by the intermediate host with the fodder or water. Upon arriving in the stomach, the eggshells are destroyed and the six-liooked embryo, which is th us freed, bores its way through the intestinal wall and wanders, actively or pas- sively (that is, carried along by the blood), to various organs of the body, liver, lungs, ovaries, bones, skull, etc., where it develops first into an aceplia- locyst, which may develop further into any of the variations given below in the description of the larval stage. The heads which are formed, upon being devoured by a dog or wolf, then develop into adult tapeworms. The larval stage develops rather slowly, and may persist for many years. Thus, cases are on record where the hydatid has existed for 2, 4, 8, 15, 18, and even 30 years in man, very often, however, with fatal results. Modifications of the hydatid cysts.—The larval stage appears iu several different forms, which have been described under various names as representing different species. It is now admitted, however, by nearly all authors, especially by zoologists, that all these forms belong to one species and have been brought about by different modes of growth. Let us assume that a six-liooked embryo has reached the liver, lungs, or some other organ of the secondary host (man, cattle, sheep, etc.). About four weeks after the infection small cysts, scarcely 1 mm. iu diameter, are noticed in the interlobular tissue of the liver, for instance. They consist of an outer cyst, formed by the connective tissue of the host, and an inner solid body, 0.25 to 0.50 mm. in diameter, which represents the young parasite. The six hooks of the embryo have been discarded and the organism consists of an outer transparent cap- sule—the cuticle—20 to 50 /1 in thickness, and a granular content somewhat con- densed on the periphery and containing cells which are not distinctly separated from one another. At the end of eight weeks the parasite has doubled in size. The cuticle, which is very elastic, grows thicker and its inner surface is covered Fig. 102.—Portion of the intestine of a dog infested with the adult Hydatid Tapeworm (Taenia echinococcus), natural size. (After Ostertag, 1895, p. 430, fig. 99.)