Protection Against Disease 



453 



Theories of Disease. In early times, diseases were supposed 

 to be carried by witches and other unfriendly spirits. In later 

 times, they were believed to come from infectious particles that 

 arose from decaying matter, stagnant marshes and filth of every 

 kind, and were carried in the air. The germ theory of disease 

 favored this belief. In recent years the theory that diseases are 

 spread by means of such things as bedding, books, discarded cloth- 

 ing, and other objects has been popular. 



The proof of the fact that 

 many of the most dangerous 

 diseases are caused by organ- 

 isms of a parasitic nature, bac- 

 teria and protozoa, now tends 

 to establish the belief that such 

 diseases come from actual con- 

 tact with these invisible germs. 

 The theory that persons and 

 not things spread disease is 

 gradually becoming an ac- 

 cepted belief. The idea that 

 disease germs retain their vi- 

 tality in bedding, books or 

 money for long periods of 

 time is no longer credited, 

 although the fact is not denied 

 that towels, dishes and other 

 objects recently used by those ill with a communicable disease 

 may be the means of transmitting germs to others. It is no 

 longer doubted that hand contact accounts largely for the spread 

 of many common diseases, and that insect contact accounts for 

 the spread of most of the rest. 



Our chief attention should be given to the prevention of con- 

 tact infection. You have undoubtedly often heard of diseases 

 that are "catching" and know that persons affected with one of 

 these diseases should be avoided, lest you yourself catch it. It is 

 not the disease, but the germ that causes the disease that is caught. 

 Each disease is caused by its own special germ. In some diseases 



Brown Bros. 



A BACTERIOLOGIST AT WORK 



