244 THE CARRIAGE OF TYPHOID FEVER BY FLIES 



their breeding places, including stable-manure, household refuse 

 and garbage." 



An outbreak of typhoid fever, which was recently reported upon 

 (October 1912) by Drs Amyot and McClenahan, occurred in the 

 Insane Asylum at Hamilton (Ontario, Canada). Since July 1912 

 there had been fourteen undoubted cases with two deaths. The 

 investigation shoAved that the flies had been the responsible agents, 

 carrying the infection from unscreened lavatories to the patients. 

 Tlje manure piles in the stables had been left exposed. 



Terry (1913) describes the very great reduction in the typhoid 

 death-rate in Jacksonville, U.S.A., which followed the control of 

 the fly-borne typhoid by compulsory rendering of privies fly-proof. 



The dissemination of Typhoid Fever, Bacterio- 

 logical Evidence. 



The bacteriological evidence, the result of exact experiments, 

 indicates conclusively the ability of flies to carry the typhoid 

 bacillus in a viable condition, not only internally but also 

 externally. 



A non-spore-bearing bacillus such as B. typhosus is less adapted 

 to external transference than a spore-bearing bacillus. It is never- 

 theless interesting to note the length of time which elapses before 

 B. typhosus is moribund. Howard (1911) states that Dr Mohles 

 informs him that B. typhosus will live in butter under common 

 market conditions for 151 days and still be able to grow when 

 transferred to suitable conditions. In milk kept under market 

 conditions they retain active mobility for twenty days ; after this 

 they lessen in numbers and finally disappear in the forty-third 

 day. An important fact is that observed by Delepine, namely, 

 that B. typhosus can remain in a viable condition on the walls of 

 a privy for twelve months. The bearing which this fact has on 

 the possibility of flies becoming infected subsequent to an- epidemic 

 of typhoid fever Avill be readily understood. 



In order to form a correct estimate of the extent to which and 

 the manner in which flies distribute pathogenic and other bacteria, 

 a study of the natural bacterial flora of the digestive tract of the 

 house-fly would appear to be desirable, if not essential. Until 



