308 The Philippine Journal of Science mis 



be based the treatment and prophylaxis of an infectious disease. 

 On account of the relatively long incubation period usually exist- 

 ing in entamoebic dysentery, the prevalence of chronic and latent 

 cases of the disease, and the frequent inefficience of treatment 

 to kill all of the entamoebse in the intestine, the microscopic 

 identification of the pathogenic Entamoeba histolytica is of par- 

 ticular importance in the diagnosis, the control of treatment, 

 and the prophylaxis of entamoebic dysentery. Hitherto, on 

 account of the uncertainty existing as to the specific entamoeba 

 concerned in the production of this disease and the supposed 

 difficulty of identifying the organism, especially in the resting 

 and encysted stage, the microscopic diagnosis of infections with 

 Entamoeba histolytica has been subject to many errors; indeed, 

 in many laboratories, no attempt is made to distinguish between 

 the pathogenic species and the common, harmless Entamoeba 

 coli, or to diagnose latent and chronic infections. An extensive 

 practical experience gained in the course of this investigation has 

 demonstrated that the microscopic diagnosis of infections with 

 Entamoeba histolytica can be made with certainty, and has dis- 

 closed many practical points in the technique and the application 

 of this diagnosis. Therefore, it is believed that a somewhat 

 extended treatment of this subject is warranted. 



The material for the microscopic examination for Entamoeba 

 histolytica should be a stool obtained, contrary to the prevailing 

 practice, without the previous administration of a purgative. 

 In stools obtained after a purgative. Entamoeba histolytica, if 

 present in the fluid stool, is in a preencysted stage at which it 

 most closely resembles the nonpathogenic species. Entamoeba 

 coli; consequently, a differential diagnosis between the two 

 species is difficult and often impossible. 



It may be objected that without a purgative infections with 

 Entamoeba histolytica will frequently be overlooked. However, 

 such is not the case. It has been my experience in following 

 many cases of entamoebic infection with daily stool examinations, 

 including cases doubly infected with Entamoeba histolytica and 

 Entamoeba coli, that the entamoebse are rarely absent from the 

 normal stools several successive days and that Entamoeba his- 

 tolytica is more constantly present, and usually present in larger 

 numbers, in the stools of infected persons than is Entamoeba 

 coli. In 930 microscopic examinations made of stools, without 

 the previous administration of a purgative, from men known 

 to be parasitized with Entamoeba histolytica, and who were not 

 undergoing treatment, the entamoebse were found 664 times, or 

 71.39 per cent ; that is, in nearly 3 out of every 4 of such exam- 



