380 SCIENCE OF HOME AND COMMUNITY 



disposing of sewage and in the purification of water is the 

 fact that even after a patient has recovered from the disease, 

 he may continue to carry typhoid germs in his body for 

 several years. These are given off in the excreta, which 

 may thus be a means of spreading the germs. Thus such a 

 person may be as dangerous to the health of a community 

 as are typhoid patients. It is estimated that one person in 

 every twenty-five who recovers from the disease continues to 

 carry these germs, sometimes for as long a period as twenty 

 years. 



Household filters. If the water supply is suspected of 

 being contaminated with typhoid germs, the surest protec- 

 tion is to boil for a half hour all water to be used for drink- 

 ing purposes. This will kill all the germs and make the 

 water safe. The great majority of the common small filters, 

 which contain sand and charcoal and are attached to the 

 faucet, are worse than useless. They do not remove the 

 bacteria from the water, and the dirt which collects becomes 

 a breeding place for bacteria. There are, however, filters 

 which will remove the typhoid bacteria. Three types are on 

 the market, the Pasteur, the Berkfield, and the Chamberlain 

 niters, all of which embody the same principle. These con- 

 tain unglazed porcelain through which water passes slowly. 

 Even these require careful attention to insure safety. They 

 should be thoroughly cleaned every day, and every fourth 

 day should be boiled five minutes so as to kill the bacteria 

 in the pores of the filter. 



Ice. It is possible for typhoid germs to be carried even 

 in ice. Freezing does not kill all the bacteria; some may 

 lie dormant for several months frozen in the ice, ready to 

 renew their activity when it melts. Whenever ice is to be 

 used for cooling water, the cleanest and safest way is to 

 put the ice around the receptacle containing the water in- 

 stead of directly in the water. 



