SPIROCH^TA PERTENUIS 63 



Yaws 



A common feature of nearly all tropical countries is the disease 

 known as yaws or frambesia. In the Fiji Islands all healthy 

 children are expected to pass through an attack of yaws and are 

 sometimes inoculated with it by their parents. It is common in 

 many parts of equatorial Africa, particularly on the West Coast. 

 In the West Indies it is also a very common disease, especially in 

 the islands which are largely inhabited by negroes. There is 

 some evidence that yaws was imported to America from Africa 

 with the slaves as were some others of the most troublesome Amer- 

 ican diseases. In Brazil the disease is called " buba brasiliensis " 

 and is often confused with Leishmanian diseases. 



The parasite which is the cause of this loathsome disease is a 

 spirochsete, Sp. pertenuis, which is hardly distinguishable from 

 the spirochsete of syphilis, and was for a long time thought to be 

 identical with it. Recent investigations, however, have shown 

 that there are some slight differences in the two parasites, though 

 not enough to be recognizable by anyone but an expert. Like 

 the spirochsete of syphilis, Sp. pertenuis inhabits many different 

 organs and tissues of the body, being found especially in the 

 spleen and lymph glands and in the tumor-like " yaws." It is 

 not yet conclusively proved that yaws and syphilis are not slightly 

 different types of the same disease, though most workers believe 

 in their distinctness, and for practical purposes, at least, it is best 

 to consider them as distinct. One of the arguments in favor of 

 the unity of the two diseases is that typical syphilis seldom occurs 

 where yaws is prevalent, and vice versa, but this may be due to 

 a reciprocal immunity, i.e., yaws giving immunity to syphilis, and 

 syphilis to yaws. 



The Disease. — In from 12 to 20 days and occasionally longer 

 after infection constitutional symptoms appear, such as fever, 

 rheumatic pains, and general illness. These symptoms are some- 

 times very severe, but usually they are slight and often hardly 

 noticeable. After several days of such symptoms there appears a 

 peculiar powdery scahng-off of the skin, sometimes almost invisible 

 but at other times making white marks, especially conspicuous 

 on the dark skin of negroes. After several days little pimples 

 appear over the hair follicles in the patches of powdery skin. 

 As these grow the raw flesh from beneath pushes the horny 



