198 



[September, 1909, 



showed that this fly;, while breeding 

 most numerously in horse stables, is also 

 attracted to human excrement and will 

 breed in this substance. It was shown 

 that in towns where the box privy was 

 still in existence the house fly is attract- 

 ed to the excrement, and, further, that 

 it is so attracted in the filthy regions 

 of a city where sanitary supervision is 

 lax, and where in low alleys and cor- 

 ners and in vacant lots excrement is 

 deposited by dirty people. He stated 

 that he had seen excrement which had 

 been deposited overnight in an alley- 

 way in South Washington swarming 

 with flies under the bright sunlight of 

 a June morning (temperature 92 F.), and 

 that within 30 feet of these deposits 

 were the open windows and doors of 

 the kitchens of two houses kept by poor 

 people, these two houses being only two 

 elements in a long row. 



The following paragraph is quoted 

 from the paper just cited :—" Now, 

 when we consider the prevalence of 

 typhoid fever, and that virulent typoid 

 bacilli may occur in the excrement of 

 an individual for some time before the 

 disease is recognized in him, and that the 

 same virulent germs may be found in the 

 excrement for a long time after the 

 apparent recovery of a patient, the 

 wonder is not that typhoid is so 

 prevalent, but that it does not prevail 

 to a much greater extent. Box privies 

 should be abolished in every com- 

 munity. The depositing of excrement 

 in the open within town or city 

 limits should be considered a punish- 

 able misdemeanour in communities which 

 have not already such regulations, and 

 it should be enforced more rigorously 

 in towns in which it is already a rule. 

 Such offences are generally committed 

 after dark, and it is often difficult or 

 even impossible to trace the offender ; 

 therefore, the regulation should be 

 carried even further, and require the 

 first responsible person who notices the 

 deposit to immediately inform the police, 

 so that it may be removed or covered 

 up. Dead animals are so reported ; 

 but human excrement is much more 

 dangerous. Boards of Health in all 

 communities should look after the 

 proper treatment or disposal of horse 

 manure, primarily in order to reduce the 

 number of house flies to a minimum, and 

 all regulations regarding the disposal of 

 garbage and foul matter should be made 

 more stringent and should be more 

 stringently enforced, 



" It is not alone as a carrier of typhoid 

 that this fly is to be feared. In the 

 same way it may carry nearly all the 

 intestinal diseases. It is a prime agent 

 in the spreading of summer dysentery, 



and in this way is unquestionably 

 responsible for the death of many 

 children in summer. One of the earliest 

 accurate scientific studies of the agency 

 of insects in the transfer of human 

 disease was in regard to flies as spreaders 

 of cholera. The belief in this agency 

 long preceded its actual proof. Dr. 

 G. F. Nicholas, in the London Lancet, 

 Volume 11, 1873, page 724, is quoted by 

 Nuttall as writing as follows regarding 

 the cholera prevailing at Malta in 1849 :— 

 1 My first impression of the possibility of 

 the transfer of the disease by flies was 

 derived from the observation of the 

 manner in whicli these voracious crea- 

 tures, present in great numbers, and 

 having equal access to the dejections and 

 food of patients, gorged themselves in- 

 discriminately, and then disgorged them- 

 selves on the food and drinking utensils. 

 In 1850 the Superb, in common with the 

 rest of* the Mediterranean squadron, was 

 at sea for nearly six months ; duriug the 

 greater part of the time she had cholera 

 on board. On putting to sea, the flies 

 were in great force ; but after a time 

 the flies gradually disappeared, and the 

 epidemic slowly subsided. On going 

 into Malta Harbour, but without com- 

 municating with the shore, the flies 

 returned in greater force, and the cholera 

 also with increased violence, After 

 more cruising at sea, the flies disappeared 

 gradually with the subsidence of the 

 disease.' " 



"With tropical dysentery and other 

 enteric diseases practically the same 

 conditions exist " 



"The typhoid fly also possesses im- 

 portance as a disseminator of the bacilli 

 of tuberculosis." This was shown to 

 occur in the following manner :— 



" 1. Flies may ingest tubercular 

 sputum and excrete tubercle bacilli, the 

 virulence of which may last for at least 

 fifteen days." 



" 2. The danger of human infection 

 from tubercular flyspecks is by the 

 ingestion of the specks on food," 



Some interesting experiments upon the 

 number of bacteria carried by flies are 

 recorded. From these it appears that — 

 " The numbers of bacteria on a single 

 fly may range all the way from 550 to 

 6,600,000, Early in the fly season the 

 numbers of bacteria on flies are compara- 

 tively small, while later the numbers are 

 comparatively very large. The place 

 where flies live also determines largely 

 the numbers that they carry. The 

 average for the 414 flies (employed in the 

 experiment) was about one and one- 

 fourth million bacteria on each. It 

 hardly seems possible for so small a bit 

 of life to carry so large a number of* 



