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THE NATIONAL GEOGRAPHIC MAGAZINE 



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 regard- 

 ing the disposal of garbage and foul mat- 

 ter should be made more stringent and 

 should be more stringently enforced." 



In the opening sentence of the para- 

 graph just quoted attention was called lo 

 the activity of bacilli in excreta passed by 

 individuals after apparent recovery from 

 typhoid. Since the paper in question was 

 published, more especial attention has 

 been drawn by medical men to this point, 

 and it has been shown that individuals 

 who are chronic spreaders of the typhoid 

 germs are much more abundant than was 

 formerly supposed. 



Dr. George A. Soper recently discov- 

 ered a striking case of this kind in the 

 person of a cook employed successively 

 by several families in the vicinity of New 

 York City, with the result that several 

 cases of typhoid occurred in each of these 

 families. In a paper by Doctor Davids 

 and Professor Walker, read before the 

 Royal Sanitary Institute of London dur- 

 ing the present season, the history was 

 given of four personal carriers of typhoid 

 who had communicated the disease to a 

 number of people. These four carriers 

 were detected in one city within a few 

 months, and from this fact it can be ar- 

 gued with justice that such cases are 

 comparatively numerous. This being 

 true, the presence of unguarded miscel- 

 laneous human excreta deposited in city 

 suburbs, in vacant lots, and in low alley- 

 ways intensifies to a very marked degree 

 the danger that the food will become con- 

 taminated with typhoid bacilli by means 

 of the typhoid or house fly. It is known, 

 too, that the urine of persons who have 

 suffered from typhoid fever often con- 



tains active typhoid bacilli for several, 

 weeks after the patients have recovered ; 

 consequently this also is a source of 

 danger. 



THE HOUSE ELY ALSO SPREADS INTESTINAL 



DISEASES, CHILDREN'S COMPLAINTS, 



AND CONSUMPTION 



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. 



In a report by Daniel D. Jackson to the 

 committee on pollution, of the Merchants' 

 Association in New York, published in 

 December, 1907, the results of numerous 

 observations upon the relation of flies to 

 intestinal diseases are published, and the 

 relation of deaths from intestinal diseases 

 in New York City to the activity and 

 prevalence of the common house fly is 

 shown not only by repeated observations 

 but also by an interesting plotting of the 

 curve of abundance of flies in comparison 

 with the plotted curve of abundance of 

 deaths from intestinal diseases, indicating 

 that the greatest number of flies occurred 

 ' in the weeks ending July 27 and August 

 3 ; also, that the deaths from intestinal 

 diseases rose above the normal at the 

 same time at which flies became preva- 

 lent, culminated at the same high point, 

 and fell off with slight lag at the time of 

 the gradual falling off of the prevalence 

 of the insects. 



The typhoid fly also possesses im- 

 portance as a disseminator of the bacilli 

 of tuberculosis. In a paper by Dr. Fred- 

 erick T. Lord, of Boston, reprinted from 

 the Boston Medical and Surgical Journal 

 for December 15, 1904, pages 651-654, 

 the following conclusions are reached : 



"1. Flies may ingest tubercular spu- 

 tum and excrete tubercle bacilli, the viru- 

 lence of which may last for at least fif- 

 teen days. 



"2. The danger of human infection 

 from tubercular flyspecks is by the inges- 

 tion of the specks on food. Spontaneous 



