122 THE ANIMAL PARASITES OF MAN 



tion and encystment are known to take place ; x transmission to 

 other hosts is effected during the encysted stage. 



Balantidium coli was discovered by Malmsten in 1857 m a 

 man aged 35 years, who had two years previously suffered from 

 cholera, and since then had been subject to diarrhoea ; the 

 examination revealed an ulcer in the rectum above the mid 

 sphincter ani, in the sanguineous purulent secretion of which 

 numerous Balantidia were swimming about. Although the ulcer 

 was made to heal, the diarrhoea did not cease and the stools 

 contained numerous balantidia, the number of which could only 

 be decreased by extensive enemas of hydrochloric acid. 



The second case related to a woman who was suffering from 

 severe colitis, and who died ten days after admission. The mal- 

 odorous, watery evacuations contained innumerable balantidia in 

 addition to pus, and at the autopsy the anterior portion of the 

 large intestine was found to be their habitat. 



Subsequently this parasite has often been observed in human 

 beings, and according to Shegalow's compilation 63 cases have been 

 recorded. These occurred as follows : 24 cases in Russia, 15 cases 

 in Scandinavia, 7 cases in Finland, 6 cases in Cochin China, 5 cases 

 in Italy, 3 cases in Germany, 2 cases in the United States, and 

 i case in the Sunda Islands. 



In addition 5 more cases came under observation in Konigs- 

 berg, Prussia (Collmann), one was incidentally mentioned by 

 Maggiora as occurring in the Province of Alexandria, and one 

 case occurred in Tomsk (Solowjew). 



In the greatest 'majority of the cases the patients suffered 

 from obstinate intestinal catarrh^ which did not always cease even 

 after the balantidia had disappeared ; whereas, on the other hand, 

 balantidia have occasionally still been found to be present, though 

 in small numbers, after the catarrh has been cured. Most authors, 

 nevertheless, do not regard balantidia as the primary cause of the 

 various diseases of the large intestine, which often commence with 

 the development of ulcers, but they consider that they may 

 aggravate these diseases and render them obstinate. According to 



1 According to Gourvitch (" Bal. coli. Darmk. d. Menschen," Russ. Arch. /. Path., 

 klin. Med. u. Pact., St. Petersb., 1896), the conjugated balantidia are supposed to amal- 

 gamate with each other and form oval cysts two or three times the size of the free 

 creatures, and to divide into numerous globules within the cystic membrane ; the 

 process, however, has hitherto not been observed. The supposed balantidium cysts 

 appeared in two patients after the administration of anthelminthic, and who were 

 simultaneously suffering from Bothriocephalus latus ; it therefore appears to me, 

 according to the description, that in reality these forms were actually abnormally 

 large, possibly swollen, young eggs of the tapeworm mentioned. 



