THE CHOLERA SPIRILLUM AND ALLIED VARIETIES 401 



As in like other infectious diseases, not everyone who is exposed to 

 infection is attacked by cholera. The bacilli have been found during 

 cholera epidemics in the dejections of healthy individuals without any 

 pathological symptoms. Abel and Claussen for example, in 14 out 

 of 17 persons belonging to the families .of 7 cholera patients, found 

 cholera vibrios, in some of them for a period of fourteen days. In 

 Hamburg there were 28 such cases of healthy choleraic individuals 

 with absolutely normal stools. It is evident, therefore, that an individual 

 susceptibility is requisite to produce the disease. In the normal healthy 

 stomach the hydrochloric acid of the gastric secretions may destroy 

 the spirilla; and, finally, the normal vital resistance of the tissue cells 

 to the action of the cholera poison may be taken into consideration. 

 According to the greater or less power of this vital resistance of the body 

 the same infectious matter may give rise to no disturbance whatever, 

 a slight diarrhoea, or it may lead to serious results. Furthermore, it 

 may be accepted as an established fact, that recovery from one attack 

 of cholera produces personal immunity to a second attack for a con- 

 siderable length of time. This does not appear to depend upon the 

 severity of the attack; for cases are recorded of persons who were appar- 

 ently not sick at all, and yet in whom an acquired immunity was pro- 

 duced. How long this immunity lasts is not positively known, but 

 probably for a month or more, so that the same person is not likely 

 to be taken ill again with cholera during an epidemic. 



On the other hand, we may take it for granted that susceptibility to 

 cholera may be acquired or increased. For instance, there is no doubt 

 that gastric and intestinal disorders produced by overeating, etc., may 

 act as contributing causes to the disease. Other predisposing causes 

 are general debility from poverty, hunger, disease, etc. 



Cholera Toxins. Koch was the first to assume, as the result of his 

 investigations, that the severe symptoms of the algid stage of cholera 

 were due to the effects of a toxin produced by the growth of the comma 

 bacillus in the intestines. 



In 1892 Pfeiffer published an account of his elaborate researches 

 relating to the cholera poison. He found that recent aerobic cultures 

 of the cholera spirillum contain a specific toxic substance which is fatal 

 to guinea-pigs in extremely small doses. There is extreme collapse, 

 with subnormal temperature. This substance stands in close relation 

 with the bacterial cells, and is perhaps an integral part of them. The 

 filtrate of a recent cholera culture contains usually only moderate 

 amounts of toxic substances. The spirilla may be killed by chloroform, 

 thymol, or by desiccation, without apparent injury to the toxic power 

 of this substance, but subjected to 60 C. some of the toxins are destroyed. 

 Metchnikoff, Roux and others have shown that living, highly virulent 

 cultures produce at times highly poisonous toxins, the 0.2 c.c. of filtrate 

 of a three to four day culture killing 100 grams of guinea-pig. The 

 living culture in 2 to 4 c.c. of nutrient bouillon contained in collodion sacs, 

 when placed in the peritoneal cavity of guinea-pigs, produced symptoms 

 of poisoning and death in a few days. Sacs containing the dead vibrios 



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