488 Chapter XV 



rises above normal, reaching 38*5° to 39° C, and sometimes even 

 40°_40*5°C. This febrile condition lasts from 15 to 48 hours. It is 

 soon accompanied by pain, redness, and swelling at the point of 

 inoculation. These symptoms persist for from three to five days. 

 The malaise which follows the vaccinations is sometimes very uncom- 

 fortable or even painful, but never serious. Only in exceptional 

 cases is the formation of abscesses observed, and this is due, undoubt- 

 edly, to contamination of the vaccines by foreign micro-organisms. 

 The English Commission sent to India to study plague found other 

 micro-organisms than the plague coccobacilli fairly frequently in the 

 [611] vaccine culture flasks, but, with very rare exceptions, these micro- 

 organisms were found to be innocuous. By rigorously following the 

 rules to be observed in making pure cultures it should not be difii- 

 cult to avoid this complication. 



Haff*kine used every efibrt to induce his patients to be vaccinated 

 a second time, being justly persuaded that two injections are capable 

 of ensuring a more certain and more stable immunity than is a single 

 injection. 



From what moment immunity may be considered to be acquired 

 has been a matter for great discussion. From very numerous experi- 

 ments upon animals of various species, as well as many observations 

 on man, it is now agreed that a period of several days (5—8) from 

 the injection of the vaccine is required before immunity is manifested. 

 It is for this reason that cases of plague which have broken out 

 before this period has elapsed cannot be looked upon as contra- 

 indicating the efficacy of the method. 



A large amount of evidence, coming from persons who have made 

 their observations on the spot, is almost unanimous in endorsing the 

 fact that Haffkine's vaccination protects man against plague. It is 

 often difficult to compile exact statistics in surroundings where so 

 many factors contribute to deceive even the careful observer. In 

 spite of this a certain amount of evidence has been collected which 

 may be accepted as affording us fairly satisfactory information. One 

 of the best groups of statistics was that collected at Damaun, 

 a Portuguese possession in India, into which plague was imported from 

 Bombay in 1897, and where a large number of vaccinations were 

 carried out. From the report of Haff'kine and Lyons ^, in a popula- 

 tion of 8230 persons, rather more than one-fourth (2197) were 

 vaccinated, the greater majority (6033) remaining uninoculated. 



1 "Joint Report on the Epidemic of Plague in Lower Damaun," Bombay, 1897. 



