2l8 TROPICAL MEDICINE AND HYGIENE 



disease and will be described separately. Associated 

 with this disease is sometimes a lupoid ulceration of the 

 skin of the face, extending by continuity from the ulcera- 

 tion of the nares. Periostitis, and chronic ulcers of the 

 legs and elsewhere have been described, as sequelae of 

 yaws. If they are results of this disease they are very 

 rare ones. Gummata probably do not occur. 



Diagnosis. At the onset of the general eruption, and 

 whilst the granulomata are still small, in cases where the 

 muscular and back pains are severe and the temperature 

 is high, the disease has been mistaken for small -pox ; such 

 errors are very rare. The disease in the majority of 

 cases has to be diagnosed from syphilis and other skin 

 diseases. In a single case the diagnosis from a fram- 

 bcesial syphilide may be impossible ; from any other 

 syphilide it is easy. The absence of ulceration, the raised 

 granulomatous tumour and the sulphur crust with the 

 milky fluid underneath it differentiate the disease from 

 rupia or similar tertiary syphilitic lesions. Where the 

 case is under observation the close similarity of the 

 successive eruptions is unlike that in syphilis. The 

 exposure to contagion, the occurrence of other cases, 

 and the absence of any other signs of syphilis all aid 

 in the diagnosis. 



Prognosis. Death may occur in children under one 

 year, or in debilitated persons, but even in such cases 

 a fatal termination is exceptional. Good feeding, cleanli- 

 ness, and protection from irritation of the yaws diminish 

 the liability to ulceration but do not shorten the course 

 of the disease. 



Pathological Anatomy. The lesions, are limited to the 

 skin and subcutaneous tissues. Essentially the growth 

 is a vascular granuloma, and there is no tendency to 

 caseation, necrosis, or suppuration. The epidermis is 

 softened, and the distinction between the various layers 

 is lost. Pigment is either not formed or irregularly 

 distributed in the deeper layers or subcutaneous tissue. 

 Keratinization is imperfect, and the superficial layers of 



