INDICATIONS FOR PASSIVE IMMUNIZATION 685 



in character to demand passive immunization. Meningococcus men- 

 ingitis may, however, be an exception, but the method of active im- 

 munization advocated by Sophian is promising, easier to carry out, and 

 should be tried during times of epidemic meningitis. 



In typhoid fever, cholera, and dysentery antibacterial serums have 

 not been generally used in prophylaxis, although it would appear that a 

 potent anticholera serum would prove of value in preventing epidemics 

 of this frightfully infectious disease. 



With the exception, therefore, of the true intoxications, prophylaxis 

 is more readily secured by active than by passive immunization. This 

 is certainly true of typhoid fever, rabies, and smallpox. The antiserums 

 of other microorganisms, such as the pneumococcus, streptococcus, and 

 gonococcus, are being used exclusively for therapeusis, rather than for 

 prophylaxis, of their several infections. 



In veterinary practice hog-cholera serum has proved of value as a 

 prophylactic means of combating and limiting epidemics of hog cholera. 

 It is not definitely known whether this serum is antitoxic or antibac- 

 terial, but it is probably a combination of both. 



In the treatment of disease immune serums have proved of value in 

 diphtheria, tetanus, cerebrospinal meningitis, and, to a lesser extent, 

 dysentery, pneumonia, streptococcus infections, and plague. 



While antipneumococcus, antistreptococcus, and antigonococcus 

 serums have proved of some value in the treatment of their particular 

 infections, the more recent work of Neufeld and Handel, Dochez and 

 Cole, and their coworkers in pneumonia indicates that there are wide 

 biologic differences among various strains of these microorganisms, and 

 that no curative properties can be expected from a given serum unless 

 this is homologous for the type causing the infection. Further than 

 this, it has been found impossible to secure serums as rich in antibodies 

 as are secured with diphtheria and tetanus antitoxins, and that the 

 serums must be given intravenously in relatively large doses. A method 

 for the quick recognition of types of pneumococci has been worked out 

 in the Rockefeller Hospital, and immune serums have been prepared for 

 the main types, and the results of the serum treatment of pneumonia 

 along these lines have been found to be most encouraging. While this 

 method is not adapted for general use, it holds out a promise for the 

 future of serum therapy, and opens up a wide field of investigation with 

 the group of streptococci, gonococci, and meningococci. 



