BALANTIDIUM COLI 



203 



suffering from entero-colitis, into which human faeces containing 

 Balantidia were introduced per os, Balantidium cysts were found in 

 the fasces three days after the last ingestion. Great numbers, more- 

 over, were found in the caecum and the posterior part of the small 

 intestine at the autopsy of the animals, which died about eight days 

 after the commencement of the experiments. Actual colonization, 

 therefore, was not effected in either series of experiments. Free or 

 encysted Balantidia of pigs were used for further experiments. The 

 experiments proved negative when faeces containing cysts were injected 

 into the rectum of healthy cats (three experiments), or cats (two) 

 suffering from spontaneous intestinal catarrh, or when such material 

 was introduced per os into three healthy cats. In the case of two 

 cats with intestinal catarrh artificially produced, a small number of the 

 active Balantidia injected into the rectum remained alive. Larger 

 quantities of faeces containing encysted Balantidia were introduced 

 into two other cats affected with the same complaint. These, certainly, 

 did not appear in the faeces, but small numbers, free and alive, were 

 found in the caecum. Similarly, encysted Balantidia were introduced 

 into two cats with dilated rectum, and whose faeces had an alkaline 

 reaction. In these cases no parasites appeared in the faeces, but three 

 and five days later, when the two animals were examined, a very small 

 number were discovered free in the large intestine. Klimenko did 

 not succeed in infection experiments with B. coll on young dogs, 

 whose intestines had been artificially affected by disease. 



More recent experiments by Brumpt have shown that young 

 sucking pigs can be infected with Balantidium from infected monkeys 

 (Macacus cynomolgus) and suffer heavily from the same, whereas the 

 Balantidium of the pig is rarely harmful to its host. This and previous 

 experiments may be thought to suggest that there are perhaps 

 several pathogenic species, and also that harmless strains of Balan- 

 tidium may occur. At the same time, it must be remembered that 

 a large proportion of the cases recorded of Balantidian colitis occur 

 among swineherds and butchers, that is, among people in frequent 

 contact with pigs. Morphologically, there are practically no differ- 

 ences between the Balantidia found in man, monkeys and pigs, and 

 it is probable that one species only, under slightly different environ- 

 mental conditions, may be responsible for the colitis observed. In 

 any case, efficient prophylactic measures should be taken against 

 balantidiasis in countries where it may occur, by confining the pigs 

 and not allowing them to run in yards and dwellings. 



E. L. Walker (1913) has given a good summary of work on 

 balantidiasis. His own researches in the Philippines showed that 

 monkeys could be infected by Balantidia both from pigs and men. 

 Parasites may appear in the stools only at infrequent intervals. He 



