DIAGNOSIS OF CHOLERA 387 



is loss from these and more from several spirilla occurring in natural 

 waters that difficulties of diagnosis arise. 



The reasons for believing Koch's bacillus to be the cause of 

 cholera are four: (a) its constant presence in cases of the 

 disease ; (&) the results of accidental infection with this bacillus ; 

 (c) the agglutinative and protective properties of the serum of cholera 

 patients ; and (d) the result of Haffkine's preventive inoculation. 



There appears to be evidence to show that comma bacilli may be 

 introduced into the alimentary canal without producing the disease, 

 unless there be some injury or disease of the wall of the intestine 

 (Peiffer). Desquamation of the intestinal epithelium seems an essential 

 factor in the production of the disease in man. It need hardly be 

 added that the bacillus acts, like other pathogenic bacteria, by the 

 production of toxins (Peiffer), which appear to be intracellular. At 

 present very little is known of their chemical nature. Brieger 

 separated cadaverin and putrescin and other bodies from cholera 

 cultures, and other workers have separated a toxalbumin. 



Methods of Diagnosis of Cholera : 



1. The nature of the evacuations and the appearance of the 

 mucous membrane of the intestine afford striking evidence in 

 favour of a positive diagnosis. Nevertheless, it is upon a minute 

 examination of the flakes and pieces of detached epithelium that 

 reliance must be placed. In these flakes will be found abundance 

 of bacilli having the size, shape, and distribution, of the specific 

 comma of cholera. The size and shape have been already referred to. 

 The distribution of comma bacilli ("fish in stream") in the 

 flakes of watery stools is, when present, somewhat characteristic of 

 Asiatic cholera, and may greatly aid in a correct diagnosis. But 

 unfortunately, it is not always present, and then search for other 

 characters must be made. 



2. The appearance of cultivation on gelatine, to which reference 

 has been made, is of diagnostic value, and the growth on agar and in 

 peptone solution. 



3. The " cholera red reaction." It is necessary that the culture 

 and the sulphuric acid be pure for successful reaction. 



4. The intra-peritoneal injection in guinea-pigs is followed by 

 abdominal distention, subnormal temperature, and other characteristic 

 symptoms. 



5. Isolation from water is, according to Dr Klein, best accom- 

 plished as follows : A large volume of water (100-500 c.c.) is placed 

 in a sterile flask, and to it is added so much of a sterile stock fluid 

 containing 10 per cent, peptone, 5 per cent, sodium chloride, as will 

 make the total water in the flask contain 1 per cent, peptone and 

 '5 per cent. salt. Then the flask is incubated at 37 C. If cholera 

 vibrios are present in the water, however few, it will be found 



