472 - CHOLERA 



The serum of an animal immunised by the above method has 

 also marked agglutinative and other antibacterial properties 

 (p. 571) against the cholera spirillum, and these properties closely 

 correspond with Pfeiffer's reaction as regards specificity. Such 

 a serum has, however, little protective effect against the toxic 

 action of the dead spirilla, and Pfeiffer maintained that little or 

 no antitoxin to the endotoxin can be produced. On the other 

 hand, Macfadyen, by injecting the endotoxin derived from the 

 spirilla by grinding, obtained a serum which had antitoxic as well 

 as agglutinative and bacteriolytic properties {vide Immunity). 

 Metchnikoff and others also obtained antitoxic sera which acted 

 on the extracellular toxins. While it may be admitted that 

 antitoxins to some of the cholera toxins may be obtained, yet 

 Pfeiffer's position, that cholera anti-sera have- little effect on 

 at least most of the endotoxins, cannot be said to be shaken. 

 It should be noted, however, that he disclaims having made the 

 general statement, often ascribed to him, that no antitoxins are 

 formed to endotoxins. 



The serum of cholera convalescents has been found to possess 

 protective and increased bactericidal action. These properties of 

 the serum may be present eight or ten days after the attack of 

 the disease, but are most marked four weeks after ; they then 

 gradually diminish. Specific agglutinative properties appear in 

 the serum of cholera patients, as in other diseases. They are 

 most marked in patients who recover, reaching the maximum in 

 from two to three weeks from the onset of the disease, the serum 

 then agglutinating in a dilution of 1 : 400 or even 1 : 1000 (Greig). 

 Agglutinins are also often present in the blood of carriers. It 

 should, however, be noted that normal serum may sometimes 

 have an agglutinating effect on the cholera organism in a dilu- 

 tion as high as L : 20. Variations in the opsonic index, analogous 

 to those in other diseases, have been observed in cholera, a 

 marked fall on the acute onset of the disease being a note- 

 worthy feature. 



Within recent times there have been introduced for therapeutic purposes 

 several so-called anti-sera which are supposed to be antitoxic as well as 

 anti-bacterial, and of these the two most extensively used are those of 

 Kraus and Schurupoff. Reports regarding the effects of these sera are of 

 somewhat conflicting character, but in any case it cannot be said that they 

 have a markedly beneficial action. They have further been critically 

 examined by others, who deny to them any marked antitoxic action when 

 tested experimentally. 



Allied Organisms. — El Tor Vibrio. — Up till recent times 

 there had been cultivated, from sources other than cholera cases, 



