64 SPIROCHETES 



epidermis up, causing it to crack over the surface in such a way 

 as to give the little tumor the appearance of a raspberry. Little 

 yellow summits soon develop on the tumors, composed not of 

 pus but of a cheesy material. Some of the pimples grow no 



further, but most of them become capped 

 over with the yellow cheesy substance 

 which catches and holds particles of dust, 

 and thus become very dirty. These are 

 the " yaws " from which the disease takes 

 its name. During their formation they 

 cause some itching, but are not painful. 

 They reach the height of their develop- 

 ment in 12 or 14 days and then usually 

 begin to shrink, the dirty yellow cap, now 

 dark colored, falling off and leaving a 

 sound patch of pale skin. Sometimes, 

 ^°" }?k \T^^ °^ ^^^^ however, though in less than ten per cent 



(After Manaon.) ' . . , 



of cases, ulceration of the yaws takes 

 place, but this is probably due to complicating infections. The 

 time that the disease lasts varies greatly according to the general 

 health and constitution of the patient. In normal mild cases it 

 may be all over in less than two months, while in weak or sickly 

 individuals crop after crop of yaws may appear for months or 

 years, recurring at irregular intervals. There is some evidence also 

 that there may be a rare tertiary stage of yaws corresponding to 

 a similar stage in syphilis, characterized by a diseased condition 

 of the bones of the arms and legs, ulcers, etc., though this may 

 often be due to mixed infections with syphQis or other diseases. 

 The disease known as gangosa, prevalent in Guam and other East 

 Indian Islands, is thought by some to be a consequence of yaws. 

 Yaws is very seldom a fatal disease except in young children. 

 Like syphilis it is very contagious, but the parasites are not 

 transmitted frona mother to baby before birth or by nursing. 



Treatment and Prevention. — Care of the general health of 

 yaws patients and conditions leading to the free eruption of 

 the yaws aid much in shortening and alleviating the course of 

 the disease. Salvarsan is poisonous for the parasites of yaws 

 as it is for other spirochsetes, and is an almost sure cure at any 

 stage of the disease when injected either into the veins or muscles. 

 In experimental animals the parasites disappear within 24 hours 



