CHOLERA 385 



of fact, we know too little as yet concerning either form to dogmatise 

 on the matter. Until 1884 practically nothing was known about 

 the etiology of cholera. In that year, however, Koch greatly added 

 to our knowledge hy isolating a spirillum from the intestine, and in 

 the dejecta of persons suffering from the disease. 



Cholera has its home in the delta of the Ganges. From this 

 endemic area it spreads in epidemics to various parts of the world, 

 often following lines of communication. Cholera is generally 

 conveyed by means of water. It is a disease which is characterised 

 by acute intestinal irritation, manifesting itself by profuse diarrhoea 

 and general systemic disturbance accompanied by collapse, cramps, 

 cardiac depression, subnormal temperature, and suppression of urine. 

 The incubation period varies from only a few hours to several days. 

 In the intestine, and setting up its pathological condition, are the 

 specific bacteria, in the general circula- 

 tion their toxic products bringing about 

 the systemic changes. 



The spirillum of Asiatic cholera 

 (Koch, 1884) generally appears in the 

 body and in artificial culture, broken 

 into bacillary elements known as 

 " commas." These are curved rods 

 with round ends, showing an almost 

 equal diameter throughout, and some- 

 times united in pairs or even in chains 

 (spirillum). The latter rarely occurs in 

 the intestine, but may be seen in fluid 



T, rrn i ir ~u> FIG. 35. Diagram of the Comma 



cultures. The common site for Koch s Bacillus of cholera. 



comma is in the intestinal wall, crowd- 

 ing the tubules of the intestinal glands situated between the epi- 

 thelium and the basement membrane, abundant in the detached 

 flakes of mucous membrane, and free in the contents of the intes- 

 tine. The bacilli are present in enormous numbers, and lie usually 

 with their long axes in the same direction, giving the "fish in 

 stream " appearance (Koch). The bacilli do not occur in the blood, 

 nor are they distributed in the organs of the body. They occur 

 mostly in the lower intestine. 



The bacillus is actively motile, and possesses at least one terminal 

 flagellum. The organism is aerobic, and liquefies gelatine. It 

 stains readily with the ordinary aniline dyes, but does not stain by 

 Gram's method. It does not produce spores, though certain refractile 

 bodies inside the protoplasm of the bacillus in old cultures have 

 been regarded as such. The virulence of the bacillus is readily 

 attenuated, and both the virulence and morphology appear to show 

 in different localities and under different conditions of artificial 



2 B 



