FLIES 



899 



With regard to the spread of B. typhosus and B. paratyphosiis 

 A and B via the larva to the fly, the only experiments of real 

 moment are those of Faichnie, who worked with uncultivated 

 germs, the flies being bred in infected faeces. He showed that 

 this was highly probable, though other workers have failed with 

 cultivated material. Faichnie, however, did not say that he 

 separated the larvae which had fed upon the excrement therefrom, 

 and therefore did not say that he had excluded the possibility of 

 the newly hatched flies feeding upon the excrement. Hence the 

 subject of the carriage from the larva to the imago is suh judice at 

 present. 



Finally, as far as is known, flies do not suffer in health from the 

 carriage of germs pathogenic to man. 



Is the fly, with its non-lactose ferment ers, the original home of the 

 enteric fevers of man ? We have not sufflcient knowledge at present 

 to discuss this subject, but we have said enough to demonstrate its 

 importance. 



For epidemiological reasons, supported by bacteriology, it appears 

 probable that ' epidemic or summer diarrhoea ' is due to Morgan's 

 bacillus spread by flies. 



For epidemiological reasons it seems possible that flies may infect 

 food with the germs of the choleras. 



There is no doubt that flies can obtain the tubercle bacillus 

 from sputum, keep it alive in the crop for three days, and in the 

 intestine for twelve or more days, and thus can contaminate food 

 by the faeces up to the fifth day, and sometimes up to the sixth to 

 fourteenth day. 



Anthrax spores remain infective in flies for twenty days, being 

 found in the faeces, while in dead flies the period is indefinite; 

 moreover, they can pass via the larva to the imago. 



At this stage we may point out that the infection of wounds 

 produced by biting flies may be carried out by the agency of non- 

 biting flies. Patton was the first to point out that non-biting flies 

 — e.g., Musca pattoni — suck the blood which exudes from the bites 

 made by tabanids, stomoxys, etc. As M. pattoni breeds in bovine 

 excrement, the possibility of bacterial infection of the wound is to 

 be remembered. 



The possibility of the Klebs-Loeffler bacillus and allied organisms 

 being spread by flies must not be forgotten, though there is no 

 evidence that this is the usual form- of infection; still, judging from 

 a case of conjunctival diphtheria seen in Khartoum by Chalmers, 

 it is possible that it may occur as the means of infection of unusual 

 sites, as Graham Smith has shown that the germ can live in the crop 

 and intestine for twenty-four hours and longer, and, further, that 

 the vitality may be under-estimated. 



Ophthalmia, for epidemiological reasons, especially the Egyptian 

 ophthalmia, is believed to be spread by flies, and Perry and Castel- 

 lani have shown that Microneurum funicolum de Meijere, 1905^ — 

 the eye-fly of Ceylon and Java — is a possible carrier of the Koch- 



