CHAPTER XXXVIII. 



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ORDER: AMGEBINA. 

 Amoeba coli (Losch). 



SEVERAL varieties of amoebae have been reported as occurring in 

 the human intestines, but as the full cycle of no one of them has 

 been worked out it is possible that some of them at least may be 

 stages in the life cycle of other protozoa. The most important one 

 among these varieties is that observed by Lambl in 1860, and more 

 fully described by Losch in 1875 as amoeba coli. Losch found it in the 

 stools of dysenteric patients, and he succeeded in producing, experi- 

 mentally, superficial ulce rations in the large intestines of dogs. He 

 therefore claimed that this organism is the cause of dysentery. 



His work was corroborated by many observers, the organism being 

 also found pure in tropical abscess of the liver; but later studies have 

 shown that this parasite does not play as important a part in dysentery 

 as was thought. It has been found that in many cases of dysentery the 

 amoeba coli is not present, that the same or similar amoebae are present 

 in the healthy stools, and that animal experiments are not satisfactory. 

 These facts, together with those brought out by the recent work of 

 Shiga, Kruse, Flexner, and others, on bacillary dysentery, have demon- 

 strated that there are at least two forms of dysentery, one produced by 

 amoebae and the other by bacilli, and that in the former case, among a 

 number of harmless varieties of intestinal amoebae, one or two only are 

 of clinical importance. According to Shiga the differential diagnosis 

 between the two varieties of dysentery is as follows: 



In amoebic dysentery (1) the disease is generally chronic; (2) no 

 dysentery bacilli are found in the feces; (3) there are not present any 

 severe toxic symptoms, such as fever (except in the case of abscess of 

 the liver), weakness, headache, anorexia, rapid emaciation, hemor- 

 rhages, etc.; (4) abscess of the liver is a frequent sequela; (5) the 

 lesion is in the caecum and descending colon ; the small intestines are 

 not affected. 



In bacillary dysentery the finding of the bacilli and the positive results 

 of agglutination tests, together with the clinical symptoms of intoxica- 

 tion, make a certain diagnosis. 



At present we may group the pathogenic niiKrba 1 under one head, 

 calling the groups amoeba coli; though Schaudinn, in his recent work on 

 the amoebae of the human intestines, has given quite a definite descrip- 

 tion of two varieties, one of which he calls entamoeba coli Losch, which 

 is a harmless comensal in the human intestines, and the other entamoeba 



