THE MICROBE OF TYPHOID FEVEE 167 



some previous patient. The germ is never com- 

 municated by the breath or by the sputum, only 

 by the excreta. Therefore could the excreta in 

 every case be promptly disinfected, all germs would 

 be killed, and the spread of the disease prevented. 



But, to say nothing of lazy people, professional 

 nurses and doctors are apt to be careless and 

 negligent. Under their direction, without disin- 

 fection, the excreta find their way, in cities, to the 

 sewer. Sewer gas, therefore, always contains the 

 germs. Occasionally the disease is traced to this 

 gas. 



A family leaves its city home for a vacation in 

 the country. During the long absence the house 

 is vacant. No water for the sewer. The water 

 seal of the sewer trap evaporates. The trap is dry. 

 Through it the sewer gas comes freely into the 

 house. With it come the typhoid germs. On the 

 return of the family, one or more members become 

 infected with the germs and have the disease. 



But how easily prevented. On leaving the 

 house open a faucet slightly. While absent, let 

 the small stream of water from this faucet contin- 

 ually flush the sewer pipe. The water seal of the 

 trap is thus kept perfect. No sewer gas enters the 

 house. No germs. The fever is avoided. 



But nearly, if not quite, all other cases come 

 from water supplies. Surface water, as ponds, 

 lakes, streams, instead of Spring water. Of course 

 Springs may be polluted with typhoid germs; but 

 they rarely, if ever, are. It is usually, if not al- 



