334 ^^6 Philippine Journal of Science isis 



this protozoan were discovered. Moreover, on account of the 

 infrequent appearance of the parasites in the stools of infected 

 persons and the absence of clinical symptoms in many of the 

 cases, it is probable that parasitization with Balantidium coli 

 is frequently overlooked in the routine examination of stools. 



The geographical distribution of this infection is wide, and 

 appears to be influenced by certain sanitary conditions rather 

 than by climate. Cases have been reported in Russia, Sweden, 

 Finland, Germany, Italy, North America, South America,. Cuba, 

 Africa, Sunda Isles, Cochin China, and the Philippine Islands. 

 It is noteworthy that most of the known cases have occurred in 

 Russia and Scandinavia, cold countries, on the one hand, and, on 

 the other hand, in a tropical country, the Philippine Islands. 



Balantidiasis in man is characterized clinically by the appear- 

 ance of Bala7itidium coli in the stools and, in a certain propor- 

 tion of the cases, by a diarrhoea or dysentery. 



However, the appearance of the parasites in the patient's 

 stools is very irregular; they may be absent for weeks at a 

 time, and they may at any time be found only in very small 

 numbers and, consequently, frequently are discovered only when 

 attention is attracted to the stools by the appearance of a persist- 

 ent diarrhoea or of dysenteric symptoms. 



The dysenteric symptoms are likewise an extremely inconstant 

 manifestation of the infection. Of the 132 human cases of 

 which I have been able to obtain access to the literature, 130 had 

 diarrhoeal or dysenteric symptoms; but it is probable that the 

 majority of these cases were brought to the attention of the 

 physician by the dysenteric symptoms and that the parasites 

 were found only in the attempts to discover the etiology of the 

 symptoms. Of the 57 cases of parasitization so far reported in 

 the Philippine Islands, only 11 have shown diarrhoeal or dysen- 

 teric symptoms. In other words, many of the infections are 

 latent. 



The mortality in 111 cases according to Strong (1904) was 32, 

 or 29 per cent. The primary cause of death in some of these 

 cases may have been other than the balantidiasis; on the other 

 hand, many of the patients passed from observation and their 

 ultimate fate was unknown. It is probable that if the patients 

 parasitized, but not infected with the parasite, be included the 

 percentage of mortality would be considerably lower, while if only 

 those patients in which there was an actual invasion of the tissues 

 by the balant^dia be considered, the death rate from balantidal 

 infection would be materially increased. The mortality in 57 



