400 BACTERIA PATHOGENIC TO MAN 



of the epithelial covering, which thus renders possible the absorption 

 of the cholera toxin formed by the growth of the spirilla. The larger 

 the surface of the mucous membrane infected and the more luxuriant the 

 development of bacilli and the production of toxin the more pronounced 

 will be the poisoning, ending fatally in a toxic paralysis of the circu- 

 latory and thermic centres. On the other hand, however, there may 

 be cases where, in spite of the large number of cholera bacilli present 

 in the dejecta, severe symptoms of intoxication may be absent. In 

 such cases the destruction of epithelium is not produced or is so slight 

 that the toxic substance absorbed is not in sufficient concentration to 

 give rise to the algid stage of the disease, or for some reason the spirilla 

 do not produce toxin to any extent. In no stage of the disease are 

 living cholera spirilla found in the organs of the body or in the secre- 

 tions. 



Distribution in the Body. The cholera spirilla are found only in the 

 intestines and are believed never to be present in the blood or internal 

 organs. The lower half of the small intestine is most affected, a large 

 part of its surface epithelium becoming shed. The flakes floating in 

 the rice-water discharges consist mostly of masses of epithelial cells 

 and mucus, among which are numerous spirilla. The spirilla also 

 penetrate the follicles of Lieberkiihn, and may be seen lying between 

 the basement-membrane and the epithelial lining, which become 

 loosened by their action. They are rarely found in the connective 

 tissue beneath, and never penetrate deeply. In more chronic cases 

 other micro-organisms play a greater part and deeper lesions of the 

 intestines may occur. 



Communicability. From this fact and other known properties of the 

 cholera spirillum, which have already been referred to, several im- 

 portant deductions may be made with regard to the mode of transmis- 

 sion of cholera infection. In the first place the bacilli evidently leave 

 the bodies of cholera patients, chiefly in the dejections during the 

 early part of the disease (they have usually disappeared after the 

 fourth to the fourteenth day), and only these dejections, therefore, 

 and objects contaminated by them, such as bed and body linen, 

 floors, vaults, soil, well-water and river-water, etc., can be regarded 

 as possible sources of infection. There is a special limitation even 

 in these sources of infection, owing to the fact that this spirillum is 

 so easily destroyed by desiccation and crowded out by saprophytic 

 organisms. Thus, as a rule, only fresh dejections and freshly con- 

 taminated objects are liable to convey infection; after they have 

 become completely dry there is little danger. Further, we must con- 

 clude from the distribution of the cholera bacillus in the body and from 

 experiments upon animals that the commonest mode of infection is by 

 way of the mouth, and chiefly by means of water used for drinking pur- 

 poses, for the preparation of food, etc. In recent times cholera spirilla 

 have been found not infrequently in water (wells, water-mains, rivers, 

 harbors, and canals) which has become contaminated by the .dejec- 

 tions of cholera patients. 



