CARRIAGE OF DISEASE 139 



plumbing ordinances often loom large as the chief 

 weapons of combating disease. Too often attention is 

 diverted from really significant and tangible dangers 

 to health by the cry that the garbage dump or the sew- 

 age manhole is emitting vile odors. It is of course 

 well known to physicians that there is no evidence that 

 disease can be spread by odors, although foul air may 

 possibly impair health and render the body less re- 

 sistant to disease. 



*'Many sanitarians are beginning to fear that a sim- 

 ilar misapplication or misunderstanding of the relation 

 of the house fly to typhoid fever is coming about. No 

 one questions that the house fly is an unmitigated nui- 

 sance. Neither is there any doubt that under certain 

 conditions, such as prevail in military or mining camps 

 or on many a country farm, or even in cities that allow 

 the crude type of privy, the house fly is an exceedingly 

 important agent in the transmission of infection. This 

 has been abundantly proved. There is observable, how- 

 ever, a tendency to assume a connection much wider 

 than this and to attribute to fly infection a portion, 

 sometimes the major portion, of the typhoid fever oc- 

 curring in large and well-sewered cities. 



"Several instances of this misguided enthusiasm have 

 come to notice within the last few months. It need 

 hardly be pointed out that the house fly, no matter how 

 disgusting its origin or habits, cannot convey the spe- 

 cific germ of typhoid fever to any food substance un- 

 less it has access both to food substances and to typhoid 

 germ. Those amateur investigators who assume that 



