CHAPTER XXIII. 



PATHOGENIC BACTERIA OUTSIDE THE BODY. 



Pathogenic bacteria may exist outside the body of the 

 host under a variety of conditions as follows: 



I. In or on inanimate objects or material. 



(a) As true saprophytes. 



(b) As facultative saprophytes. 



(c) Though obligate parasites they exist in a latent 



state. 



II. In or on other animals or products from them: 



A. Susceptible to the disease, 

 (a) Sick themselves. 



(As far as human beings are concerned these are 

 mainly : 



1. Other human beings for most diseases. 



2. Rats for plague. 



3. Dogs for rabies. 



4. Horses for glanders. 



5. Cattle, swine, parrots for tuberculosis). 

 (6) Recovered from illness. 



(c) Never sick but ''carriers." 



B. Not susceptible. 



(d) Accidental carriers. 



{e) Serving as necessary intermediate hosts for certain 



stages of the parasite— this applies to lyrotozoal 



diseases only, as yet. 



I. (a) The bacilli of tetanus, malignant edema and the 



organisms of "gas gangrene" are widely distributed. There 



is no evidence that their entrance into the body is at all 



necessary for the continuation of their life processes or that 



one case of either of these diseases ever has any connection 



with any other case; they are true saprophytes. Mani- 



(233) 



