Fleas and Plague 145 



After the consideration of the evidence from 

 various sources the commission decided that the 

 principal mode of infection both for man and rats 

 was through some sort of an abrasion in the skin, 

 although it recognized also the possibility of in- 

 fection through the nose and throat, and possibly, 

 very rarely, through the intestinal tract or other 

 places. 



Considerable time was spent in considering Dr. 

 Simond's claim, made in 1898, that fleas which 

 have been parasitic on plague-infected rats migrate 

 on the death of their hosts and convey the infection 

 to healthy men and rats. Dr. Simond sought to 

 establish the following: 



"Firstly, that plague rats are eminently infective 

 when infected with fleas and that they cease to be in- 

 fective when they have been deserted by their parasites : 

 Secondly, that living plague bacilli are found in asso- 

 ciation with fleas which are taken from plague-infected 

 rats: Thirdly, that plague can pass from infected rats 

 to other animals which have not come directly in 

 contact with them or with their infected excretions: 

 Fourthly, that fleas which infest rats will transfer 

 themselves as parasites to men." 



After reviewing the experiments which had been 

 made to establish these claims the commission be- 

 lieved that sufficient precaution had not been 



