Rat fleas, body lice and wood ticks are known carriers of serious diseases; 

 we can fight these diseases most effectively by fighting the carriers and rats or 

 other secondary hosts. 



As the average span of life is lengthened by improved nutrition and the 

 prevention of communicable diseases, there is an increase of "old age" diseases, 

 resulting from deterioration of tissues or organs. Studies of these conditions 

 point to better ways of managing our lives. 



There is a limit to the use of scientific knowledge by the individual or by 

 the family; co-operation with others is increasingly necessary both to prevent 

 the spread of communicable diseases and to ensure adequate water supplies, 

 disposal of sewage and wastes, and other essential services. 



Increasingly we depend upon joint supervision, regulation, and direct 

 services by public agencies to protect and promote the health of the com- 

 munity and of its members. 



Our actual health conditions, because of fixed habits, customs, and ideas or 

 **beliefs", lag behind those that scientific knowledge might make possible. 



EXPLORATIONS AND PROJECTS 



1 To find out the chief causes of ill health, investigate mortality and morbidity 

 tables from the departments of health of your city or state, from the United States 

 Public Health Service, and from the statistical reports of various insurance com- 

 panies. Information can be obtained on the number of cases of infectious diseases 

 and on the chief causes of death at different age levels. Supplement these data with a 

 study of the severity, nature and control of each of the more frequent causes of ill 

 health or death. 



2 To find how medical care is provided, read and discuss various publications of 

 the United States Public Health Service and of the American Medical Association, 

 and also various Public Affairs Pamphlets. Organize material and arrange to discuss 

 how the public can best assure itself of needed health and medical services. 



3 To determine the relative number of bacteria in various waters, collect in 

 sterilized bottles samples of water from near-by lakes, streams, swimming pools, 

 wells, cisterns, and city-supply taps. Bring samples to the laboratory immediately 

 and place in a refrigerator. Dilute 1 cc of each sample in 99 cc of sterile water.. 

 Shake each dilution thoroughly; then pour 1 cc of the dilution into a sterile Petri 

 dish and add sterile liquid nutrient agar.^ It is well to make duplicate cultures of 

 each sample. Allow cultures to harden and then place upside down in a warm part of 

 the room. Examine in 48 hours. By counting the colonies, determine the number of 

 bacteria present in each sample of water. 



^To prepare desiccated nutrient agar for use, dissolve 25 g of the powder in 1 1 of boiling 

 water. Place some of the nutrient agar in each Petri dish and sterilize the Petri dishes by keeping 

 them in a steam bath for 30 min or in a pressure cooker at 15-pounds pressure for 20 min. 



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