YAWS AND SYPHILIS 2 19 



epidermis are cast off, and form the scab covering the 

 granuloma. The cause of the peculiar yellow colour is 

 unknown. In moist situations in the neighbourhood of 

 the genitals or mouth there is little or no scab formation, 

 and superficial ulceration is common. 



Treatment. Salvarsan has an extraordinary effect in 

 reducing the duration of the disease. Mercury and 

 arsenic in their inorganic combination certainly do not. 

 Potassium iodide is uncertain in its action. The erup- 

 tions will sometimes disappear rapidly when iodides are 

 given, but even in such cases when the use of the drug 

 is continued fresh eruptions appear. The value of iodides 

 is therefore limited, but salvarsan causes a rapid dis- 

 appearance of the lesions. Local applications that 

 merely serve to keep the granuloma clean are valuable, 

 but escharotics and irritants, though they may destroy 

 the yaws, are likely to cause the formation of scars. The 

 painful granulomata on the feet are best destroyed by the 

 action of nitric acid, acid nitrate of mercury, or silver 

 nitrate. 



Etiology. Most observers who have had extensive 

 experience of the disease known as yaws consider it to 

 be a clinical entity. Some eminent authorities, and 

 especially Hutchinson, believe it to be syphilis, and that 

 the differences from the common manifestations of that 

 protean disease as seen in temperate regions are due 

 to the effect of climate, race and heredity in the Tropics. 



The similarity of the two diseases will be admitted by 

 all. In both there is a rather prolonged period of incu- 

 bation with a primary sore, rarely absent in syphilis, 

 commonly absent in yaws, and a series cf cutaneous 

 eruptions lasting for months or years, with later manifesta- 

 tions usually of a destructive character, which are common 

 in untreated syphilis, and also in yaws if the lupoid dis- 

 eases of the mucous membrane are correctly attributed to 

 the antecedent yaws. The parasitic cause of syphilis is now 

 generally believed to be a spirochaete, Spirochcvta pallida, 

 and a spirochaete morphologically indistinguishable 



