CHAPTER XVI 

 HUMAN DISEASES 



INTRODUCTION 



THIS chapter does not pretend to be in any way exhaustive. 

 A full account of human diseases in Africa could be prepared 

 only by a body of experts, and would be unsuitable for the present 

 purpose, which is to indicate briefly the ways in which the study 

 of human disease relates to other branches of science. 



While the African is subject to most diseases which are known 

 in temperate regions, he is particularly a sufferer from others 

 which are unknown or have disappeared wholly or partially from 

 Europe, and are now looked upon as 'tropical diseases'. These 

 have been classified most commonly according to their methods 

 of transmission, but for the purposes of this survey and to empha- 

 size as strongly as possible the methods by which they can be 

 controlled, a better grouping would be as follows: 



A. Those diseases which are primarily due to the conditions of life 

 of primitive agricultural peoples, and which may be expected 

 to disappear with the introduction of improved social conditions 

 and communal organization. Such diseases are malaria, black- 

 water fever, the jungle type of yellow fever, sleeping sickness. 



B. Those diseases which are primarily due to the existence of 

 insanitary conditions, and which may be expected to disappear 

 with the introduction of improved housing, water-supplies, 

 conservancy, etc. Such diseases are plague, relapsing fever, 

 typhus, tuberculosis, leprosy, helminthiasis, typhoid, dysentery, 

 pneumonia, and yaws. 



C. Those diseases, the spread of which is largely due to ignorance. 

 Among such the most important are the venereal diseases. 



D. Those diseases which are, or are suspected to be, due to mal- 



