BALANTIDIUM COLI I PIG 



balantidia from two monkeys on May 2y. On May 30 

 the pig passed cysts ; from June 2 to 23 large numbers of 

 the cihates were passed; diarrhea occurred on June 11 

 and red blood cells appeared in the stools on June 12. 

 When killed and examined on June 23 lesions were found 

 in the large intestine, presumably due to the presence of 

 the ciliates, that were similar in every way to those pre- 

 viously described by various investigators in man. Ohi 

 (1923) claims that the indigenous pigs of Southern 

 Formosa that are infected with B. coli appear sickly as 

 compared with uninfected animals. Six pigs injected 

 with balantidial material either by mouth or rectum did 

 not become infected but one pig that received injections 

 by both mouth and rectum became infected, and, al- 

 though it showed no symptoms, pathological changes 

 supposedly due to the ciliates were found in the large 

 intestine when the animal was killed 172 days later. 



Besides the morphological evidence that B. coli in man 

 and the pig belong to the same species, there is strong 

 epidemiological evidence that human beings become in- 

 fected by ingesting specimens from pigs rather than from 

 man. In the first place, as Brug (1919b) has pointed out, 

 cysts which no doubt are usually responsible for the in- 

 fection of new hosts, appear to be more rare in man than 

 in pigs. Secondly, a large percentage of human cases can 

 be traced more or less definitely to pigs. Thus of 117 

 cases of balantidiosis listed by Strong (1904) twenty- 

 five per cent had either been associated with pigs or had 

 eaten or prepared fresh sausage. Recently reported cases 

 ofifer similar evidence. Young and Walker (1918) re- 

 port a patient who worked in a packing house as a gut- 



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