290 HEALTH AND DISEASE 



Do not let any one who is ill assist in preparing food. 



Do not eat or drink from utensils used by others. 



Wash the hands immediately before eating. 



Keep the general health good through proper exercise, 

 fresh air and wholesome food. 



Disinfection. Since all the microbes producing dis- 

 ease are living organisms which must have favorable con- 

 ditions for their growth and development, it is possible 

 to provide the unfavorable conditions which will check 

 their growth or even kill them outright. When the 

 microbes are in the body, this is done, as we have seen, 

 by the development or injection of antibodies. When, 

 however, the microbes are outside of the body, as, for 

 example, in excretions and on clothing and furniture, 

 much more immediate and vigorous measures can be 

 used. The most effective of these is moist heat in the 

 form of steam, especially if the steam is under pressure. 1 

 A few minutes' exposure to such steam is sufficient to 

 kill all microbes. Next to steam in efficiency is boiling 

 in water in a closed vessel. For all microbes except those 

 of consumption, ten minutes or so of boiling is sufficient ; 

 for the bacilli of consumption, an hour is necessary. 

 Objects which cannot be either steamed or boiled, have 

 to be treated with such chemicals as will kill the microbes 

 on them. Of these, formaldehyde 2 is the most effective, 

 both in its gaseous and liquid forms. 



Prevention of disease by municipal hygiene. No 

 matter how much care the individual exercises, it is 

 not possible for him fully to protect himself against 

 the possibility of infection, since in every community 



1 That is, in a steam-tight vessel. 



2 Formalin candles can be obtained of any druggist and when 

 used according to directions afford a most effective and simple 

 means of room and clothing disinfection, provided that penetra- 

 tion of thick clothing, etc., is not required. 



