BACTERIA IN DISEASE. 1 55 



Bodily Conditions that Dispose to Infection. — The 



development of an infectious disease may be favored by certain 

 bodily conditions. Hunger, cold and exhaustion make the body 

 more liable to the inroads of pathogenic bacteria; so also do 

 anemia and chronic diseases. Those suffering from diabetes, 

 as is well known, are especially liable to infection by the pus- 

 producing bacteria and the bacillus tuberculosis. Dr. Roswell 

 Park believes that prolonged anesthesia makes patients who 

 have undergone operations more liable to surgical infections, 

 and that absorption of bacterial poisons and auto-intoxication 

 due to the products of disordered metabolism of the patient's 

 own cells predispose to infection. Some of the above-men- 

 tioned conditions can be imitated in laboratory experiments. 

 Hens in a normal condition are not susceptible to the anthrax 

 bacillus, but Pasteur succeeded in making them contract anthrax 

 by artificially cooling them. Frogs, on the other hand, which 

 also are resistant to anthrax, may be made susceptible by keeping 

 them at an abnormally high temperature. Rats were made 

 more susceptible to anthrax by physical exhaustion produced 

 by making them run a treadmill, and pigeons by starvation. 



Abbott found "that the normal vital resistance of rabbits to 

 infection by streptococcus pyogenes is markedly diminished 

 through the influence of alcohol, when given daily to the stage 

 of acute intoxication." It was less noticeable for bacillus coli 

 communis, and not observed for staphylococcus pyogenes aureus. 

 Pigeons and other animals have been made susceptible to an- 

 thrax by intoxicating doses of alcohol. 



Climate and altitude appear to influence the liability to in- 

 fection with the tubercle bacillus, which occurs less commonly 

 in Colorado and some other elevated regions than in lower and 

 more densely populated districts. 



There are probably a great many other as yet obscure con- 

 ditions affecting predisposition to infection. 



Age. — In general, infants are more susceptible to infections 



