THE HOUSE-FLY 17 



cretes, produces the conditions that give rise to the char- 

 acteristic symptoms of typhoid fever, namely, an increas- 

 ing and fluctuating temperature, rose rash over the 

 abdomen, diarrhea or constipation, and occasionally 

 hemorrhages of the intestines. The peculiar and vitally 

 important thing about the bacillus causing the disease is, 

 that it may be present in the alimentary canal of a human 

 being some time before the individual becomes ill and may 

 remain long after the patient has entirely recovered. 

 Moreover, the bacilli, when present in an individual, 

 may be given off in the feces and in the urine. Thus, an 

 individual may be giving off these bacilli of typhoid fever 

 days before taking to the bed, and weeks or months or 

 even years, in the case of a "walking typhoid" patient, 

 after recovery. If the excreta or urine containing these 

 bacilli are deposited where they are accessible to flies, 

 for instance in open privies, the chances are high that 

 the bacilli will be carried on the bodies of these insects 

 back to our kitchens and dining-rooms and be deposited 

 on our food. During the Spanish-American War, flies 

 were traced by their whitened feet, from the lime-sprinkled, 

 open latrines, or privies, to the dining tables of the soldiers 

 in camp. 



It makes one shudder to think of the thousands of open 

 closets in the towns of the United States to which flies 

 have access and in which they breed and from which they 

 may come direct to our kitchens and dining-rooms. 



CHRONIC CARRIERS 



As stated in the foregoing, it has been known for some 

 time that the bacilli of typhoid might be given off before 



