51 8 SCIENCE IN AFRICA 



nutrition, and may be expected to disappear with an improved 

 standard of living. Such diseases are tropical ulcer, scurvy, 

 pellagra, beri-beri, xerophthalmia, and a number of other con- 

 ditions. 



In the following pages the above order has been adhered to as 

 closely as possible, but in certain cases, as in yaws and syphilis, 

 the symptoms of, and research on the diseases are so similar that 

 they have had to be considered under one heading. Diseases which 

 result from malnutrition are considered not here but in the section 

 of Chapter XVII on food and nutrition. 



RESEARCH AND CONTROL 



MALARIA 



It is often stated that malaria is holding back the advance of 

 both black and white in Africa more than any other single factor 

 — that it ought to be eradicated, controlled or at least mitigated; 

 but for the purposes of this account the aspects of the problem 

 which are implied by the word 'control' cannot be considered 

 satisfactorily because conditions, and, therefore, means of control, 

 vary greatly from place to place. It is possible only to consider the 

 general relations of malaria to human progress by stating the views 

 of some experts purely objectively and by referring to a few 

 important publications. Expert opinion can be quoted in support 

 of two policies; that which seeks to eradicate the mosquito by 

 drainage or by oiling waters, and that which concentrates on 

 killing the parasites in the sick person by quinine or other drugs. It 

 is not always recognized, especially among the general public, that 

 different workers write about different places, and that what is 

 right for one place is quite wrong for another. The League of 

 Nations malaria reports (see later) emphasize that each locality 

 must 'work out its own salvation' in the choice of anti-malarial 

 measures, and the necessity for local variations of method is now 

 recognized. 



Sir Ronald Ross, after his discovery in 1897 that part of the 

 malaria parasite's life cycle is passed in Anopheles, pointed out that 

 this knowledge provided an entirely new method of prevention 

 through the destruction of the mosquito. The Ross Institute, 



