﻿316 STRONG. 



that can be employed in India for the extermination of the malady. 

 And while in combating this disease the ordinal hygienic measures 

 should in my opinion certainly not be neglected and special attention 

 should be given to disinfection and particularly to the destruction of rats 

 and fleas, yet it must be borne in mind that in spite of all these precau- 

 tions plague may continue to exist as it has and one might almost say 

 will continue to exist in India until the larger portion of the susceptible 

 population is either protected artificially by vaccination or naturally by 

 an attack of the disease, or until the agents which transmit the malady 

 become exhausted. 



As the disease spreads and the organism becomes widely disseminated 

 in new districts and new countries, if the same conditions for the 

 transmission of the malady are to be encountered in the newly infected 

 regions, we must not be surprised if the same virulence and the same 

 high mortality continue. Only through the destruction of the bacillus 

 and of the means by which it is conveyed to man (rats, fleas, etc.) 

 and through the exhaustion of the supply of the more susceptible human 

 beings, does it appear that some epidemics of plague may be limited. 

 As long as the organisms in these epidemics are sufficiently disseminated 

 and properly conveyed to man, the epidemics may continue for indefinite 

 periods. In other words, there is not the same hope of a plague epidemic 

 wearing itself out, so to speak, as there is of a cholera epidemic doing so. 



On the other hand, it is well known that the severe epidemics of 

 the disease may be preceded by sporadic cases of mild plague, and that 

 glandular swellings in cases free of fever have also frequently been reported 

 to exist, before a more general outbreak of plague appears in malignant 

 form. The malady may also increase in virulence if it occurs in the 

 same locality in successive years, as was witnessed in the epidemic at 

 Bombay in 1896—97. We also know, as has been pointed out by Simp- 

 son, 115 that plague may begin in a new locality, then pass into a very 

 virulent variety and after reaching epidemic proportions, gradually return 

 to a mild form of the disease ; or, on the other hand, that some epidemics 

 may be mild and others malignant throughout. 



In this connection it is interesting to observe that J. F. Payne 118 

 goes so far as to distinguish two distinct strains of plague : First, the 

 Eastern Asiatic strain, distinguished b} r — ■ 



(1) The frequent occurrence of epidemics of Pestis minor or mild plague; (2) 

 the absence of any observed connection with the epizootic disease of rodents; 

 (3) more self-limited epidemics; (4) consequently less marked power of ex- 

 tension, for the eastern Asiatic epidemics have not in modern times traveled very 

 far; (5) on the whole less virulence and a lower percentage mortality. 



115 Treatise on Plague (1905), 159. Cambridge. 



U6 Allbutt & Rolleston, System of Medicine (1907), 2, 388. 



