THE RELATION OF BACTERIA TO DISEASE (35 



Conditions resulting after the entrance of bacteria 

 into the body may be defined as follows: Infection is 

 best considered as the presence of disease-producing 

 germs and the evidence of their effects. Intoxication 

 is the condition due to the poisons elaborated by 

 bacteria. Bacteremia is the mere presence of bacteria 

 in the blood while septicemia is the circulation of 

 bacteria and their products in the blood, with some 

 involvement of all the organs in the body. Pyemia 

 is similar to the last but includes the production of 

 many abscesses throughout the body. Fever may be 

 described as a disturbance by bacterial poisons of the 

 mechanism in the brain which controls the heat of the 

 body. 



Some bacteria merely multiply in the body and 

 exert their effect simply by their mechanical presence 

 without any peculiar poison. Others have the power 

 of elaborating poisons which are specific or individual 

 and whose effect is added to that of the bacterial bodies. 

 The latter form the larger percentage, and it is with 

 them we shall deal chiefly. The ability of bacteria 

 to cause disease is spoken of as their virulence. Each 

 individual kind of bacterium produces only one form 

 of disease, and always that one form. In the early 

 history of pathological bacteriology Koch elaborated 

 certain rules or postulates by which the relation of 

 bacteria to disease is determined. They are essentially 

 that the same bacterium should always be found in 

 the same clinical disease, produce this disease when 

 injected into animals, be recovered again from the 

 animals, and retain its biological characters. By this 

 means the peculiar expression of bacterial disease has 

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