11 



however, according to Ledingham, B. typhosns leads a 

 precarious existence in competition with the natural bacterial 

 flora of the larvae and pupae. 



There are numerous recorded instances in which the patho- 

 genic organisms of cholera, typhoid fever, phthisis, anthrax, 

 and plague have been recovered from the interior or dejec- 

 tions of flies which have been captured in the immediate 

 neighbourhood of cases of the disease, or in the last two, 

 of carcasses of animals dead from the disease. Cholera 

 vibrios were isolated from wild flies under these circum- 

 stances by Tizzoni and Cattani (1886), Simmonds (1892), and 

 Tsuzuki (1904) ; typhoid bacilli by Hamilton (1903), Ficker 

 (1903), Faichnie (on seven occasions) (1909), Cochrane (1912), 

 and Bertarelli (1910); tubercle bacilli by Spillmann and 

 Haushalter (1886), Hofmann (1888), Lord (1904), Hayward 

 (1904), Cobb (1905), and Buchanan (1907) ; anthrax by 

 Cao; and plague bacilli by Yersin (1894) and Hunter 

 (1906). The spread of ophthalmia in hot countries has, on 

 good grounds, been attributed to the agency of flies in 

 carrying the Koch- Weeks bacillus and the gonococcus from 

 eye to eye (Budd (1862), Laveran (1880), Howe (1888), and 

 Axenfeld (1907) ). The seasonal and local prevalence of 

 ophthalmia corresponds with that of flies, and a visit to 

 Egypt during the fly season is sufficient to convince one that 

 this must happen. 



ARE FLIES THE DETERMINING FACTOR IN EPIDEMICS ? 



Although, however, flies may be discovered with the infec- 

 tion of a number of diseases in or upon them, and by their 

 habits may not unlikely serve as agents in transferring infec- 

 tion, it by no means follows that they are the determining 

 factor of epidemicity in the case of cholera, typhoid, 

 dysentery, &c. In the case of fulminating epidemics of 

 typhoid and cholera associated with an infected water-supply 

 this is obviously not so. 



Flies in Relation to Typhoid fever. 



The conclusion that fly transmission is the principal means 

 of spread of typhoid fever in military encampments and 

 stations has been arrived at by a number of competent 

 observers, amongst them being Veeder (1898), Heed, 

 Vaughan, and Shakespeare (1901, in their report on the 

 Origin and Spread of Typhoid Fever in the United States 

 Military Camps during the Spanish War of 1898), Tooth and 

 Calverley Smith (1903), Purdy (1909), and Wanhill (quoted by 

 Purdy). 



The sanitary arrangements of a military camp are not 

 exactly those of the Ritz Hotel, and the prevalence of flies 



