Beef measles is rather common in Germany, but rare in France, Switzerland, and Italy.
TRICHINIASIS—TRICHINOSIS.
Trichinosis is a disease caused by the entrance into the body of the Trichina spiralis. This parasite is swallowed in the larval form, and undergoes sexual changes in the intestine, at first producing intestinal trichinosis, which represents the first phase in the development of the disease.
The trichinæ breed rapidly. The embryos penetrate into or are directly deposited in the blood-vessels, which convey them to all parts of the body, thus setting up the second phase of the disease, known as muscular trichinosis.
Fig. 44.—Gravid segment of beef-measle tapeworm (Tænia saginata), showing lateral branches of the uterus, enlarged. (Stiles, Annual Report U.S.A. Bureau of Agriculture, 1901.)
Fig. 45.—Egg of beef-measle tapeworm (Tænia saginata), with thick egg-shell (embryophore), containing the six-hooked embryo (oncosphere), enlarged. (After Leuckart.)
Trichinosis as a disease has long been recognised. Peacock in 1828 and J. Hilton in 1832 mentioned the existence of the cysts of trichinæ; Owen in 1835 gave the name of Trichina spiralis to the parasites contained in the cysts. Trichinosis being common in Germany at that time, Virchow and Leuckart undertook its investigation, but mistook other nematodes of the intestine for the Trichina spiralis. In 1847 Leydy recognised that trichinosis occurred in American pigs.
In 1860 Zenker found muscular and intestinal trichinosis on post-mortem examination of a girl who had been suspected of suffering from typhoid fever, and a carefully conducted inquiry revealed the fact that this girl had some time previously eaten a quantity of raw ham. Virchow and Leuckart returned to their investigations, and the life history of the parasite soon became definitely known.