CHOLERA DIAGNOSIS 1 15 



recently been recommended as a selective medium for cholera enrichment. Greig 

 found one cholera convalescent excreting cholera vibrios 44 days after the attack. 

 Of twenty-seven persons who had been in contact with cholera patients six 

 were excreting cholera vibrios though apparently well. 



To identify such spirilla immunity reactions are necessary: 



1. Injected intraperitoneally into guinea-pigs, it produces a perit- 

 onitis and subnormal temperature. This reaction exists for 

 spirilla other than the true cholera spirillum. 



2. Intramuscular injections into pigeons are only slightly patho- 

 genic, if at all. 



3. The agglutination test is the most practical. In this we use serum 

 from an immunized animal, in dilution of from 100 to 1000. It is 

 rare that true cholera vibrios fail to agglutinate in serum of i to 

 500 and even sera of i to 10,000 dilution give the reaction. Serum 

 of cholera convalescents may show agglutination as early as the 

 tenth day; it is usually best shown about the third week. Dunbar's 

 quick method is very practical. Make two hanging-drop prepa- 

 rations, using mucus from the stool as the bacillary emulsion. To 

 one add an equal amount of a i : 50 normal serum; to the other a 

 i : 500 dilution of immune serum. Cholera spirilla remain motile 

 in the control, but lose motility and become agglutinated in the 

 preparation with the immune serum. 



4. Pfeiffer's phenomenon. If cholera spirilla are introduced into the 

 peritoneal cavity of immunized guinea-pigs (or if together with a 

 i : 1000 dilution of immune serum the mixture is injected intra- 

 peritoneally into normal guinea-pigs) and at periods of ten to 

 sixty minutes after injection, material is removed by a pipette from 

 the peritoneal cavity, the spirilla have lost motility, have become 

 granular and degenerated. Pseudospirilla are unchanged. This 

 reaction may be carried on in a pipette, using fresh serum. 



Antisera for the treatment of cholera have not proved successful. Prophylac- 

 tically, there are two prominent methods: i. That of Haffkine, where live cholera 

 spirilla are injected subcutaneously; and 2. Strong's cholera autolysate. In this 

 cholera cultures are killed at 60 C. The killed culture is then allowed to digest 

 itself in the incubator at 37 C. for three or four days (peptonization). The prepara- 

 tion is then filtered and from 2 to 5 c.c. of the filtrate is injected. Ferran was the 

 first to use vaccines. 



For diagnosis : i . take a fleck of mucus, make a straight smear and 

 fix; stain with a i : 10 carbol fuchsin. The comma-shaped organisms 

 appear as fish swimming in a stream. 



