DISINFECTION. 411 



with regard to endemic diseases, such as typhoid fever, 

 whooping-cough, tuberculosis, etc. These also may attain 

 epidemic distribution. The duty of notification, which de- 

 volves upon the physician, renders it possible for the 

 authorities to have cognizance of every extraordinary in- 

 crease in the prevalence of any infectious disease, and to 

 recognize the epidemic at the outset, to trace its causes 

 and eventually to remove them. An important part of the 

 prophylactic measures against disease that already prevails 

 lies within the control of the physician. He should en- 

 deavor to prevent the increase of an endemic disease to the 

 proportions of an epidemic, and, when the disease is intro- 

 duced from without, to prevent its further extension by 

 suppressing the source of infection, by rendering the indi- 

 vidual case harmless. Disinfection, the destruction of dis- 

 ease-germs, with which every case of disease threatens its 

 immediate and remote environment, is an integral element 

 of all disease-prophylaxis. 



In the preceding chapters it has been pointed out in de- 

 tail how the germs of disease pass over into the secretions 

 and excretions, how they adhere to beds, to linen, and to 

 sick-rooms, etc. It has also been pointed out how they 

 become deposited upon articles of food and with these gain 

 entrance into other organisms. All of these carriers of 

 disease-germs should be subjected to disinfection in every 

 case of disease. 



The agents for disinfection act mechanically or chemically. 

 Those of the first group are aimed at the removal of the 

 disease-germs mechanically (by brushing, rubbing, washing, 

 rinsing, scouring, etc.), or at their destruction directly (by 

 drying, exposure to the sun, or to the action of heat). Of 

 these mechanical means the first, washing with brushes and 

 soap, etc., are in common employ. Exposure to the sun 

 (airing of beds, etc.) is probably efficient, but can influence 

 only the bacteria lying superficially. Heat may be em- 

 ployed in the form of hot or boiling water, of hot air, and 

 of steam. Boiling water is an active disinfectant, destroy- 

 ing bacteria generally within a few seconds, and particu- 

 larly resistant forms apart from the spores of harmless 

 potato-bacilli (mesentericus) in from two to five minutes. 

 Hot air is much less efficient. According to Koch and 

 Wolffhiigel, the most resistant of the spore-free bacteria 

 are destroyed by exposure for one and a half hours to air 



