576 POPULAR SCIENCE MONTHLY. 



THE BUBONIC PLAGUE. 



By FREDERICK G. NOVY, Sc.D., M.D., 



JUNIOR PROFESSOR OF HYGIENE AND PHYSIOLOGICAL CHEMISTRY IN THE UNIVERSITY OF MICHIGAN. 



THE province of Yunnan in China adjoins French Tonkin and Brit- 

 ish Burmah. It is of interest to the student of epidemiology be- 

 cause from this mountainous and difficultly accessible region there has 

 issued but recently a disease which has been considered as practically 

 extinct. Frightful as have been the ravages of the pest in the middle 

 ages, it is noteworthy that during the past hundred years, with the ex- 

 ception of two slight outbreaks (Noja in Italy in 1815, and Vetlianka 

 in Eussia in 1878), the disease has been unknown in Europe. During 

 this time the pest has not been extinct, but has existed to a greater or 

 less extent in certain parts of Asia and in Africa. Four and possibly 

 five of these endemic foci are known to-day. The province of Yunnan 

 is one of these regions. The mountainous district of Gurhwal, lying 

 along the southern slope of the Himalayas, is another center where the 

 pest has continued to prevail. The recent travels of Koch in eastern 

 Africa have brought to light a third region about Lake Victoria, in the 

 British province of Uganda, and the German Kisiba, where the plague 

 has existed from time immemorial, cut off as it were from the outer 

 world. Only last year Sakharoff called attention to a fourth focus in 

 northeastern China, and it is quite likely that a fifth focus exists in 

 Arabia. These regions are of great importance in so far as the exist- 

 ence of permenent endemic foci sheds not a little light upon the devel- 

 opment and spread of those great epidemics which, like great tidal 

 waves, have in the past swept over whole countries and even continents. 

 It is not known when or from whence the pest was first introduced 

 into Yunnan. Unquestionably, it has existed in the extreme western 

 parts of the province for many decades. Eventually the disease spread 

 throughout the province, and frightful ravages are known to have oc- 

 curred in 1871-73. Bepeated visitations of this dread disease have 

 taught the natives of Yunnan, as well as those of Gurhwal and of 

 Uganda, to desert their villages as soon as an unusual mortality is 

 found to prevail among the rats. In spite of the frequent recurrence 

 of the plague, it did not spread to neighboring provinces, largely be- 

 cause of the fact that little or no communication exists between Yun- 

 nan and the adjoining Chinese states. Becently, however, the plague 

 did succeed in crossing the frontier, and, in so doing, it has given rise 



