CONTROL OF INFECTIOUS DISEASES. 693 



way this insusceptibility originate (natural, acquired by a previous attack, 

 or acquired by artificial treatment) the existence of insusceptibility pre- 

 vents the acquiring of the disease. 



CONTROL or INFECTIOUS DISEASES PRACTICE. 



Undoubtedly, the one wholly efficient method of preventing the spread 

 of infectious diseases would consist in immunizing all the possible in- 

 fectees against all the possible diseases. Unfortunately, we know of no 

 practical immunizing methods except in the case of a very few diseases, 

 notably smallpox. 



Our methods of control of any disease therefore begin with the attempt 

 to destroy them at their origin in the body of the patient, but such methods 

 are merely incidental to the destruction of the germs for the good of the 

 patient himself, i. e. they belong rather to therapeusis than to public 

 health. Unfortunately, also, scarcely any method of destroying bacteria 

 within the body of the patient without destroying the patient also are 

 unknown and therapeusis along this line contents itself largely as yet 

 in so controlling the patent's condition as to permit and encourage to the 

 highest the natural forces of the body in their attacks upon the germs. 

 These natural forces, however, direct their chief energies and secure their 

 chief results, not in destroying the germ but in neutralizing the poisons 

 they throw off, and in practice, patients recover rather because they have 

 neutralized the poisons than because they have killed or ejected the germs. 

 For this reason a recovered patient often remains a breeding ground for 

 the germs which caused the attack, but to whose poisons he is now re- 

 sistant or immune. 



Practically, then, the germs must leave the patient's body before they 

 can be destroyed. It is at this stage that the most efficient control can 

 be exercised, and that control consists in catching and killing them before 

 they become scattered. In practice the efficient disinfection of all the 

 discharges of a patient will prevent the spread of any disease from him. 

 But this is not as easy to do as at first might appear. Ridding the body 

 of its discharges in health is a process dependent on the individual, 

 carried out by him consciously or unconsciously all his life, and by 

 methods chiefly acquired to conserve convenience rather than to prevent 

 their spread. In health, the scattering of these discharges is not of great 

 moment, but of course the habits of miscellaneous careless discharge 

 while well, persist after disease is contracted also. The presence in the 



