RODENTS IN RELATION TO THE TRANSMISSION OF 

 BUBONIC PLAGUE. 



By Surgeon RUPERT BLUE, 



United States Public Health and Marine- Hospital Service. 



Man has associated the rat with bubonic plague since the dawn of 

 history. The monuments and coins of the earliest times yield abun^ 

 dant evidence of this association. ^Esculapius, the god of the healing 

 art, is represented by the Greeks with a rat at his feet. An early 

 scriptural reference may be found in the first Book of Samuel in the 

 fifth and sixth chapters. The historian records therein the occur- 

 rence of a fatal epidemic of "emerods" in the land of the Philistines 

 coincident with an invasion of "mice." 



The inhabitants of southern China in recent times have learned to 

 look upon the finding of sick and dead rats in their homes as a har- 

 binger of evil, in fact, as a forerunner of that dread scourge "wan- 

 yick," or plague. In the villages and cities of the Kwantung and 

 Kwangsi provinces, as recorded by medical missionaries, epizootic 

 plague almost invariably precedes an outbreak among human beings. 

 So well is this fact known to the common people that many seek 

 safety in flight, feeling assured that in a short time "yang-tzu" or 

 "wan-yick" will claim a harvest of victims among those who remain. 



Doctor Mahe, sanitary officer for the port of Constantinople, in 

 1889, called attention to the fact that epidemics of plague were always 

 announced by a great mortality among rats and mice. In 1894 

 Yersin reported the fatal epizootic among rats then prevailing in 

 Canton and Hongkong coincident with the outbreak of plague among 

 the Chinese. Recent researches have confirmed these observations 

 and a great deal has been added to the literature of plague, especially 

 in relation to its mode of transmission. Indeed, it should be said 

 that wherever the disease has prevailed in recent years the relation 

 of rats to its spread has been observed, and that since the discovery 

 of the specific bacillus by Yersin and Kitasato, in 1894, bacteriolog- 

 ical investigations have shown that there is no difference mor- 

 phologically or culturally between the bacilli of human and rat plague. 



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