238 PASSIVE IMMUNIZATION 



STREPTOCOCCUS INFECTIONS 



Since the days when v. Behring first came forward with the 

 announcement that it is possible with the serum of an animal 

 that had been immunized against the corresponding toxin, not 

 only to protect individuals against diphtheria, but even to cure 

 the disease after this has once developed, attempt after attempt has 

 been made to produce an effective antiserum also against strepto- 

 coccus infections. But as yet, the problem has not been solved. 

 Much work of value has been accomplished, but still more remains 

 to be done. That it is possible to protect animals against a fatal 

 infection with streptococci by means of a corresponding antiserum, 

 had been shown by v. Behring himself in 1892, and shortly after, 

 a number of French observers attempted to influence the infection 

 in the human being also in a similar manner. 



The most noteworthy of these early attempts are intimately con- 

 nected with the name of Marmoreck. This investigator, believing 

 in the unity of practically all the different types of streptococci 

 which are pathogenic for man, succeeded in increasing the virulence 

 of an angina strain by animal passage to such a degree that .000000001 

 c.c. was sufficient to kill a rabbit with acute symptoms. With this 

 strain he immunized horses and sheep and then recommended the 

 resulting antiserum which is thus a monovalent serum for the treat- 

 ment of all forms of streptococcus infections occurring in the human 

 being. The results, however, were practically nil. 



If we come to investigate the reasons which may be responsible 

 for this want of action, different possibilities suggest themselves. 

 On the one hand it is conceivable that the identity of the different 

 strains is only apparent and that Marmoreck's serum was inactive 

 merely because it was monovalent, i. e., because it had been produced 

 with but a single strain. If this were so it would evidently be 

 necessary to prepare a polyvalent antiserum, i. e., to immunize 

 animals with as many different strains as possible/ and to use the 

 resultant product. Or, one might imagine that in consequence of 

 animal passage, to increase the virulence of a different strain, the 

 organism could become so altered in its biological properties that its 

 virulence for the human being would be diminished or lost, and that 

 the corresponding antiserum, though active for the animals through 



