THE INEFFICIENCY OF BACTERIAL VIRUSES IN THE 

 EXTERMINATION OF RATS. 



By M. J. RosENAu, 



Surgeon, U. S. Public Health and Marine-Hospital Service, Washington, D. C, now 

 Professor of Preventive Medicine, Harvard University Medical School. 



INTRODUCTION. 



Rats are notoriously resistant to bacterial infections. About the 

 only exception is the plague bacillus. Plague among rats occurs 

 both in endemic and epidemic form. When we recall that this 

 virulent disease, which spreads readily from rat to rat, neither eradi- 

 cates these rodents nor, as a rule, makes any appreciable inroads on 

 the number of rats, we can hardly expect that an artificially induced 

 bacterial disease would be successful. No other known bacterial infec- 

 tion has such a virulence for rats as the plague bacillus has maintained. 

 Epizootics of bacterial nature, therefore, can not be classed among 

 the natural enemies of the rat. Despite this fact persistent efforts 

 have been made to create artificial epizootics to combat these danger- 

 ous and destructive rodents, but with little success. 



The bacterial viruses that have been used for the destruction of 

 rats and mice belong to the colon-typhoid group" and excite enteritis 

 of different characters and a septicemia. 



In 1889 Loeffler discovered and described a bacillus which he called 

 the bacillus of mouse typhoid {B. typhi murium). He isolated this 

 organism from a spontaneous epidemic which occurred among white 

 mice in the Hygienic Institute at Griefswald.' He determined that 

 this bacillus not only caused the death of his mice in the laboratory, 

 but also that the infection was taken into the system of the mouse 

 by ingestion. He found the cultures to be especially virulent for 

 field mice {Arvicola arvalis). Loefiier gives a complete description 



"More particularly the hog-cholera group, which includes the para-typhoid 

 organisms. 



b Loeffler, F. : Ueber Epidemieen unter den im hygienischen Institute zu Griefswald 

 gehalten Mausen und tiber die Bekampfung der Feldmausplage. Centblt. f. Bakt., 

 Grig., vol. 11, 1892, pp. 129-141. 



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