﻿REPORT ON CHOLERA IN MANILA. 427 



cases without any serious illness resulting. Between April, 1896 and 1899, 

 somewhat more than 6,500 cases were vaccinated in this manner. Powell, in a 

 report of these cases in 1899, showed that among 6,549 nonvaccinated individuals 

 there were 198 cases and 124 deaths from cholera, while among 5,778 of the 

 vaccinated there were only 27 cases and 14 deaths. 



Haffkine points out that while the vaccinated individual is obviously less apt 

 to contract cholera than the nonvaccinated, if the former should actually be 

 striken with the disease he is as likely to succumb to it as the latter (since no 

 marked antitoxic immunity has been produced by the vaccination) . The im- 

 munity following the vaccination may persist for fourteen months, after which 

 time it diminishes and probably disappears. During the period of active im- 

 munity the number of eases of cholera among the vaccinated is but one-tenth of 

 that observed in the uninoculated. 



The statistics which Haffkine quotes in his paper conclusively prove the value 

 of protective inoculation against this disease. 



We see from this review of the recent work on protective inoculation 

 against cholera that three observers, all from Bern, have reported upon 

 the value of cholera nucleo-proteid as a means of immunization against 

 the disease and have performed numerous experiments showing that anti- 

 bodies enter into the blood sera of animals inoculated with this form of 

 prophylactic. From single inoculations in rabbits, sera having as high 

 an agglutinative value as 1 : 500 and a bactericidal one of 5 milligrams 

 were obtained, but none were higher. However, these values are some- 

 what low when compared with those I have encountered in rabbits after 

 a single inoculation of the prophylactic I have described. 



Turning now to the experiments which have been performed by other 

 observers, it may be seen that no very extensive studies other than my 

 own have been made with the immunizing substances of the cholera 

 spirillum obtained and separated by autolysis, either in man or animals. 

 All of those who have reported upon the use of the method have ap- 

 parently lost sight of what seems to me to be its most important 

 advantage, namely, that when the immunizing substances are extracted 

 from the cholera organism they may be injected in much larger amounts 

 at one time than if the whole organism is used. I have inoculated 

 myself with three oesen (6 milligrams) of a living, virident, cholera 

 organism at a single dose, and the local and general reaction experienced 

 was such as to make me conclude that a larger amount than this would 

 not be practicable nor desirable as a method for general inoculation. On 

 the other hand, as I have pointed out, our routine method of human 

 inoculation consists of the injection of the immunizing substances in 

 colloidal suspension or in solution, extracted from 60 to 70 milligrams 

 of the bacteria. Obviously, we are not able to separate and obtain all 

 the receptors of the organism by the method I have employed. This was 

 demostrated by my earlier experiments, when it was shown that ^ oese 

 of the living organisms furnished as good immune sera as the receptors 

 extracted from 2 oesen of the same culture. However, the receptors 



