CHOLERA 



133 



On gelatin stabs the liquefaction produces a turnip-like hollow at the top of the 

 puncture the air bubble appearance. It gives the nitroso-indol reaction with sul- 

 phuric acid alone (cholera red). Kraus attaches importance to the fact that cholera 

 does not produce a haemolytic ring on blood agar as do the pseudocholera spirilla- 

 a difficulty is that many pseudospirilla do not haemolize. Furthermore, true cholera 

 strains may occasionally show haemolysis, especially in laboratory cultures. Quite 

 a discussion has arisen in connection with a spirillum isolated from cases of diarrhoea 

 (no symptoms of cholera) in pilgrims at El Tor. This organism gave the immunity 

 reactions (agglutination) of true cholera but on account of its haemolytic power has 

 been considered as distinct from cholera. Such a view would seem to be untenable. 

 Sp. cholera grows very rapidly on peptone solution and this is 

 the medium for the enrichment test to be later described. On 

 this it may form a pellicle. On agar the colony is more opales- 

 cent (more of a translucent grayish blue) than the typhoid. It 

 does not grow on potato except at incubator temperature. It 

 does not coagulate or turn acid litmus milk. Some strains, 

 however, do produce a certain amount of acid. Using the Hiss 

 serum sugar media our strains produced acid in glucose and 

 saccharose but not in lactose. No gas production in any of the 

 sugars. The spirilla are found in myriads in the rice-water 

 discharges, these white flakes being desquamated epithelial 

 cells. They penetrate the crypts of Lieberkuhn, but rarely ex- 

 tend to the submucosa. The symptoms are due to an endo- 

 toxin. 



Cholera may be transmitted from water supplies, 

 when the outbreak is apt to be widespread and in 

 great numbers from the start. Also by indirect con- FlG 39 ._s p i- 

 tagion, as by flies or on lettuce, etc. A very im- rillum of cholera 

 portant point is that we have well persons whose g^atin^two^day" 



fseces contain virulent cholera spirilla (cholera old. (Fraenkel 



. and Pfeiffer.) 



carriers). 



Cholera spirilla disappear from the stools of cholera patients very 

 rapidly, usually in five to ten days. 



Only exceptionally are organisms excreted longer than three or four weeks, but cases 

 are on record of periods approximating two or three months. Cholera carriers in good 

 health may come down with cholera as the result of administration of purgatives 

 or alimentary canal disorder. This would explain periods of incubation longer 

 than the usual one of two to five days. 



Cholera carriers are therefore of less importance epidemiologically 

 than typhoid carriers, where carrier stage may last years. 



It is well to remember, however, that cases have been reported of positive findings 

 after a period approximating two months from the onset of the attack of cholera. 

 Another important consideration is that the vibrios may be absent at one examina- 

 tion and be present at a later one. Purgatives seem to influence the reappearance 



