34 INFECTION 



nor is it probable that he would contract tetanus by swallowing 

 tetanus bacilli, but the reverse of these conditions certainly produces 

 infection. 



Infection may be caused from without the body, or from within. 

 Lockjaw, sepsis, hydrophobia, or anthrax may follow injuries from 

 rusty nails, splinters, weapons, unsterile fingers, or instruments. 

 Personal intercourse, bites, kisses, sexual intercourse, association 

 with persons suffering from exanthematous or contagious diseases 

 may transmit disease. 



Winslow has found colon bacilli upon 9 percent of the hands he 

 examined. Tubercle bacilli have been found on the hands of the 

 non-tuberculous. Some organisms, notably the smegma bacillus, 

 pyocyaneus bacilli and cocci resembling the white pus former, may 

 be said to be normal inhabitants of the skin. 



The bites of insects that are intermediate hosts of infectious agents 

 (plague bacilli, malarial organisms, etc.) are sources of infection 

 from without, as is also the ingestion of infected food or water. 



Infection from within may be caused by the migration of bacteria 

 from the skin inwards, or from any of the mucous membranes, on 

 which, and in which many pathogenic bacteria at all times may be 

 found. 



Bacteria from the mouth, stomach, intestines and the rectum may 

 invade the tissues and the blood under certain conditions. This is 

 particularly the case during the last stages of diseases, not necessarily 

 infectious, such as chronic heart disease, kidney disease, or diabetes. 

 Vital resistance is much lowered, and intestinal bacteria, invading 

 the tissues in enormous numbers, set up what is known as terminal 

 infection, which is often the immediate cause of death. 



The stomach with its gastric juice, containing during digestion 

 .2 percent to .3 percent of hydrochloric acid, guards the lower ali- 

 mentary tract against infection. A great many bacteria are ingested 

 with foods, particularly with milk, cheese, and over-ripe fruit. 

 These in the most part are quickly destroyed by the hydrochloric 

 acid. When the stomach is diseased and the contents become 



