86 



ORIENTAL PLAGUE 



CHAP. 



In the four years, 1898-1901, 3408 vessels left Bombay for 

 ports out of India. On the voyage plague appeared on board 20 of 

 these vessels. It was observed in man alone in 16 of the 20; in 

 both man and rats in 3 ; and in 1 in rats alone. In detail, the 

 figures are as follows : — 



[I note here, in fairness to Bombay, that it is not clear in some 

 of the above instances that the infection had been derived from 

 Bombay.] 



These figures as regards Bombay shipping suggest, it will be 

 seen, the same inference as do those concerning shipping in general. 

 And they possess a special interest, since the measures I have 

 quoted as in force at Bombay in respect of ships outward bound 

 for ports out of India comprise nothing specially intended to 

 secure destruction of rats on board ship. This notwithstanding, 

 known appearance of plague among rats on board these vessels 

 was extremely rare. 



There is another consideration to be borne in mind, the effect 

 of which is to minimise still further, in relation with alleged appear- 

 ances of plague among rats on board ship, the apprehended degree 

 of danger of transmission of this disease by rats from shore to 

 ship. In not a few of the instances which I have elected to class 

 as 'Plague among rats,' because narrators of the circumstances 

 chose to so regard it, the evidence of this depends wholly upon the 

 existence of notable mortality among rats, or, at best, upon micro- 

 scopical examination alone ; while, in other instances, it is not clear 

 that adequate bacteriological examination, physiologically confirmed, 

 had been made. But we know, from experience in this country, 

 that notable mortality among rats on board ship is not neces- 

 sarily due to plague, but may be caused by other maladies in no 



