274 BACTERIA, YEASTS, AND MOLDS 



including the hair as well as the rest of the body. The 

 person should be given clean clothes that have not only 

 been thoroughly washed but disinfected by proper means ; 

 after which there is no danger of his transmitting the 

 disease to others. 



Sewage. Since the discharges from patients find their 

 way into sewage, this material is extremely dangerous, 

 indeed from the standpoint of human health one of the 

 most dangerous of all substances. Every effort should 

 be made in the household to guard against it. Par- 

 ticular attention should be given to keeping the drinking- 

 water supply from becoming contaminated with sewage. 

 In cases where the water is from a well there should be 

 especial precautions against contamination from privies or 

 sewage. The health of the family depends upon having 

 the well a long distance from sewage and privies. 



In cities the sewage empties commonly into one gen- 

 eral system, and most of the houses are connected by a 

 series of underground channels. These sewers carry the 

 discharges from all the patients in the city, and hence 

 contain the dangerous disease germs. Since each house 

 is connected with this system of sewerage, it is of the 

 greatest importance in modern cities that the connections 

 with the sewer pipes should be most carefully guarded. 

 Proper plumbing of the approved type does this satis- 

 factorily. All bowls, sinks, and closets should be con- 

 nected with the sewer by traps. The general design of 

 such a trap is shown in Fig. 80. Between the bowl or 

 sink and the sewer is a bent tube filled with water. 

 As long as this trap is thoroughly filled with water no 

 bacteria and no gas can pass from the sewer into the sink. 



