TRICHINELLA SPIRALIS 423 



because he 'has found Trichinella of the muscles in these animals 

 after they had been fed on encysted specimens. A high temperature 

 (30 C.) must be provided in which to keep the experimental animals 

 to ensure the success of the infection. 



History. Encapsuled Trichinellse had been observed in London by Peacock 

 (1828) and by J. Hilton (1833) in the muscular system of man ; soon after 

 (1835), Paget found them in London in an Italian who had died of tuberculosis, 

 and recognized them to be encysted entozoa, which R. Owen described as Trichina 

 spiralis. Soon after, some further observations were reported on the occurrence of 

 encysted Trichinellae, in man* in England, Berlin, Heidelberg, Denmark, North 

 America ; they were also found in the pig (Leidy, Philadelphia) and the cat (Herbst, 

 Gottingen, and Gurlt, Berlin). Herbst even succeeded in infecting a badger with 

 encysted Trichinellse, and subsequently infected two dogs with the flesh of this 

 badger (1850). In 1855 R. Leuckart (Giessen) also commenced feeding experiments, 

 and, like Kiichenmeister and Virchow (1859), first went on the wrong track because 

 it was believed at that time that Trichinellae were the larvae either of Trichocephalus 

 or Strongylus. Nevertheless, these experiments yielded some important results ; 

 they showed that Trichinellae become adult in the intestine within a few days, and 

 that the females are viviparous (Leuckart). Until that time Trichinellae had been 

 regarded as fairly harmless guests of man, but opinions soon changed when Zenker 

 in Dresden (January, 1860), in performing the autopsy of a girl, aged 10, who had 

 entered the hospital with typhoid symptoms and there died, found Trichinellae (not 

 yet encysted) in the muscles ; the intestinal lesions characteristic of typhoid were 

 lacking, but numerous adult Trichinellse were found in the intestine. Inquiries 

 elicited the fact that at about Christmas time the girl had been taken ill after eating 

 pork, and at the same time the butcher from whom the meat was brought as well 

 as several of his customers fell sick : the pickled pieces of the same meat were full 

 of Trichinellae. In the face of this information it was not difficult to ascertain the 

 cause of the disease and the manner of infection in Zenker's case, and it was not 

 long before Leuckart, Virchow and Zenker were able by renewed experiments to 

 demonstrate the cycle of development of Trichinella spiralis. Similar investigations 

 followed by Glaus in Wiirzburg, Davaine in Paris, Fuchs and Pagenstecher in 

 Heidelberg, etc. 



Hardly had Zenker's case been published than numerous observations on 

 trichinosis in man appeared, some referring to isolated cases, others to small or 

 great epidemics, and nearly all from North Germany. The worst epidemic was 

 that of Hadersleben (1865), in which place, numbering hardly 2,000 inhabitants, 

 337 persons were taken ill within a short time, and of these 101 died. The source 

 of infection proved to be a single pig, the flesh of which had been mixed with that 

 of three other pigs : 200 of the badly infected persons had exclusively eaten raw 

 pork. 



Moreover, it soon became clear that epidemics of trichinosis had been observed 

 in Germany prior to 1860, but that their nature had not been recognized, although 

 in a few cases Trichinellae had been found in the muscles of those who had 

 succumbed. 



HISTORY OF THE DEVELOPMENT OF Trichinella spiralis. 



Shortly after their introduction into the intestine of experimental 

 animals the encysted Trichinellae escape from their capsules, which 

 are destroyed by the gastric juices, and they then enter the duodenum 



