204 ACTIVE IMMUNIZATION 



PLAGUE. 



Attempts at prophylactic vaccination against plague have likewise 

 led to encouraging results. Haffkine, who has done a great deal of 

 the pioneer work in this direction, thus gives some very convincing 

 figures: In the city of Hubli (British India), numbering about 47,427 

 inhabitants, vaccination was begun on the llth of May, 1898. From 

 this date until the 27th of September 38,712 individuals had been 

 vaccinated, and of these 339, i. e., 0.8 per cent., died. Of the non- 

 vaccinated during the same period 2395 succumbed, i. e., 5 per cent., 

 as compared with the total number of inhabitants. During the week 

 of September 21 to September 27, when all the inhabitants, with 

 the exception of 603, had finally been vaccinated, there were among 

 the 38,712 protected individuals only 20 deaths, while of the 603 

 non-vaccinated persons 58, i. e., 9.61 per cent., died. 



Quite striking also are the following data: In three villages there 

 occurred 13 cases among 365 vaccinated persons, with 3 deaths, 

 while of the 363 non-inoculated individuals 49 were taken ill and 38 

 died. In Bombay there developed 18 cases of the disease among 

 8200 vaccinated persons, with 2 deaths (mortality 11.1 per cent.), 

 while the general mortality from the disease was over 90 per cent. 



These few examples will, I think, suffice to illustrate the real value 

 of vaccination against plague, but it will be noted, as in anticholera 

 vaccination, that the protection is not absolute. The mortality 

 among the vaccinated is so much lower, however, i. e., 11 to 41 per 

 cent., as compared with 50 to 92 per cent, among the non-vaccinated, 

 as observed in different localities, that this factor in itself would 

 establish the value of the procedure, and as a matter of fact all the 

 different commissions, which have investigated the Haffkine method, 

 have expressed themselves in this sense. 



The Duration of Protection. This is estimated at several months, 

 after which the vaccination must be repeated, if danger of infection 

 still exists. 



Preparation of the Vaccine (Haffkine). Haffkine makes use of 

 bouillon cultures which have been allowed to grow for six weeks at a 

 temperature of 25 to 30 C. The bouillon is prepared as follows: 

 1000 grams of lean (goat) meat are passed through a meat-hashing 

 machine, and are digested for three hours with 125 grams of hydro- 

 chloric acid (concent.) in the autoclave, at a pressure of three atmos- 



