62 RELATION OF BACTERIA TO DISEASE 



poisons are specifically called endotoxins. Some bacteria 

 (cholera for example) develop both kinds. 



The local gross effects of bacterial invasion are expressed 

 in inflammation, which is greatest in those which act by their 

 mechanical presence in a confined locality, usually aided by 

 some of the poisons mentioned above. 



Bacterial poisons, it might be said, usually express some 

 definite predilection for special organs or tissues; for instance, 

 the tetanus toxins attack the brain, the streptococci attack 

 red blood cells, and the typhoid bacillus settles in the lymph 

 glands of the small intestines. 



Incubation. After bacteria have gained their foothold 

 there is a certain lapse of time until their effects become 

 evident. This is the incubation time. Its length depends 

 upon the number of organisms entering, their virulence, and 

 the resistance of the body. 



Mixed Infection. Sometimes there is more than one kind 

 of bacterium in an infection. This is called a mixed infection, 

 and although there is the expression of both causes, one 

 usually predominates. This usually results from the entrance 

 of the second invader, owing to the lowered resistance of the 

 body produced by the first invader. 



Transmission of Disease. The transmission of diseases 

 from one individual to another takes place in various ways, 

 but it may be said in general that the means of transference 

 must present conditions favorable for the retention of viru- 

 lence on the part of the bacteria. Some bacteria, notably 

 gonococci and influenza bacilli, die very quickly when dried 

 or exposed to direct light. On the other hand, tubercle 

 bacilli resist drying and diffuse light for several days. Cough- 

 ing and spitting transfer infective organisms from the mouth 

 to the air, and persons in the vicinity may receive them. 

 Clothes soiled with discharges, both urine and feces, from 

 typhoid patients, contain the bacilli and are capable of carry- 

 ing the disease. Scales from the skin in the acute eruptive 

 diseases of children may transmit infection. Milk and water 



