THE OUTLOOK OF PUBLIC HEALTH WORK 



virtual elimination from it of such diseases as malaria and 

 pellagra within a year or two. 



The science of epidemiology, properly so designated 

 within the past few decades, deals also primarily with man, 

 although secondarily it draws in a great number of related 

 subjects. It is a branch of demography- — the study of disease 

 in populations. Epidemiology, which in its methods deals 

 first with the individual, and then assembles and analyzes 

 similar data concerning a large number of individuals, 

 has proved fruitful in recent years not only in permitting 

 the formulation of generalizations concerning diseases, 

 but also in pointing to the most profitable line of attack, 

 both in research by laboratory methods and in the applica- 

 tion of control measures. For example, epidemiology shows 

 pellagra to be a disease essentially of the poor, not trans- 

 missible, seasonally limited, and associated with dietaries 

 of scanty variety. Laboratory studies directed along the 

 lines so suggested prove that the disease is caused by the 

 deficiency of a particular food principle in the diet, and 

 that it may be prevented and cured by providing foods 

 containing that principle. As another example, polio- 

 myelitis (infantile paralysis) may be cited. Epidemiology 

 shows that it spreads in populations after the manner of 

 infections, disregards social and economic status, and is 

 characterized during epidemics by the production of an 

 enormously disproportionate number of light cases and 

 healthy carriers. On the basis of this information public 

 health must recognize the futility of attempts to prevent 

 its spread by restraining the liberties of individuals, and 

 must concentrate on the early recognition of cases and the 

 institution of appropriate treatment, and on research to 

 improve or perfect present methods of specific prevention 

 and treatment. 



An enormous proportion of human disease is due to the 

 fact that we live in a world containing other forms of life 



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