70 EVOLUTION OF THE INFECTIOUS DISEASES 



perhaps anticipate a two-fold result, a certain degree of 

 immunity for an infection by inoculation and a refractory 

 state for an infection by ingestion. 



PARATYPHOID FEVERS. 



The evolution of these diseases is as a rule very analogous 

 to that of typhoid fever. So that it is sufficient to repeat in a 

 few words the differences sometimes observed in those dis- 

 eases caused by paratyphoid which are commonly called 

 "ptomaine poisoning." In these cases the ingestion of 

 infected food is followed very rapidly in a few hours by a 

 violent crisis which simulates an acute attack of cholera. 

 When all the elements are analyzed it is found that the 

 evolution of these crises is only a repetition of the typical 

 evolution of a normal typhoid infection. There is no incu- 

 bation period; the disease begins full blown. The differences 

 in the progress of the evolution of infection will be determined 

 in the two cases : 



1. By the difference of the ingested infecting dose. 



2. By the degree of the permeability of the intestinal 

 mucosa at the moment of infection, and 



3. Especially by the preexistence of a certain quantity 

 of antibodies in the blood. 



Bacteria ingested in massive doses are in part destroyed 

 and in part digested. The colloidal products of this digestion 

 pass rapidly into the intestinal mucosa and into the blood 

 causing congestion and facilitating the passage of living 

 bacteria. Bacteria in the blood are rapidly "sensitized" by 

 antibodies in excess and autolized and the crisis may be 

 terminated by death or recovery in a few hours or few days 

 at most. Repeated intravenous injection of specific antigens 

 or heterologous antigens should be the most appropriate 

 treatment in these cases. 



CHOLERA. 



The same point of view of the pathogenicity of the evolu- 

 tion of intestinal infectious infections which we have just 



