322 



PERSONAL AND CIVIC HYGIENE 



or pottery, may harbor germs in the cracks in such numbers as 

 to be a dangerous means of introducing them into our bodies. 



3. Note that such diseases as smallpox, scarlet fever, and 

 consumption may be taken by breathing the germs of these 

 diseases in with air, and so are called contagious diseases. The 

 healthy thus acquire the diseases by coming near the sick or 



tuberculosis lockjaw pneumonia typhoid 



sore throat diphtheria sleeping sickness 



boils leprosy grippe 



malaria 



FIG. 81. Germs that cause various diseases. Highly magnified. (After 



Davison.) 



where they have been. Malaria and such diseases are non- 

 contagious, as they require the bite of an insect or at least the 

 breaking of the skin in order to introduce the disease. They 

 are also infectious, as they are caused by tiny parasites which feed 

 on the human body as a host. Such diseases as diabetes and 

 insanity are noninfectious as they are not caused by parasites. 



4. What disease germs may enter the body from drinking 

 water or milk ? 



5. What might happen if the excreta from a typhoid patient 

 was thrown out near the sources of streams that supply villages 

 lower down with water ? 



6. Explain how such excreta may be disinfected. 



