288 The Philippine Journal of Science 1923 



an infectious disease is not necessarily a serious obstacle in 

 attempting its control; the development of immunity is much 

 more important, being in many cases almost an essential factor. 

 This desideratum of immunity is at least partially fullnlled in 

 yaws. The tendency to recurrence or reinfection after treat- 

 ment is not great, amounting to about 5 per cent in practical 

 work. Moreover, we have experimental evidence that the long- 

 standing cases develop sufficient immunity to afford some degree 

 of protection. 



Clinically, it would seem that a certain proportion of yaws 

 cases could be put, at least tentatively, in the rather unusual 

 classification of a chronic self-limited disease. 



A yaws clinic affords a distinct opportunity in the field of 

 public-health nursing. The self-evident characteristics of the 

 disease and its mode of attacking a community provide a clear, 

 graphic illustration of the elementary precautions essential in 

 personal hygiene. The enthusiastic cooperation of the patients 

 makes them anxious to carry out any practical recommenda- 

 tions. The experience of having once had yaws teaches them 

 the consequences of neglect and becomes an object lesson not 

 easily forgotten. 



In conclusion, we have no hesitancy in selecting yaws, with- 

 out reservation, as the one outstanding disease of the Tropics 

 through which the immediate confidence and enthusiasm of the 

 people can be secured in public-health work. It fulfills in very 

 fair measure the varied psychological and scientific require- 

 ments essential for the control of an infectious disease. 



It seems reasonable to suppose that systematic effort, sus- 

 tained over a period of a few years, would accomplish even 

 the eradication of yaws from a given locality. There are many 

 more or less isolated regions or individual islands in the Phil- 

 ippines where the feasibility of eradication could be tested 

 experimentally. 



Lastly, one's understanding of the two treponemal diseases 

 cannot be completed by a study of either yaws or syphilis alone. 

 Efforts in the control of yaws may properly be regarded as a step 

 in the direction of that infinitely more-difficult problem, the 

 control of syphilis. 



ACKNOWLEDGMENTS 



It is a pleasure to thank Commander Reynolds Hayden, 

 United States Navy, for the opportunity of cooperating in the 

 work on yaws in Santo Domingo. This work was greatly facil- 



