234 The Philippine Journal of Science 



The question of establishing spontaneous cure presents some 

 difficulties. On several occasions, children showing a typical 

 infection of yaws were brought to the clinic at Paranaque by 

 their parents who stated clearly that they themselves had had 

 yaws in childhood and recovered spontaneously without any 

 sequelae They had full confidence in their immunity and 

 handled their children without fear of reinfection. The Wasser- 

 mann reaction of six of these adults was taken and found to 

 be negative in all but two instances. 



Briefly, we feel convinced that in a large number of cases 

 the disease terminates spontaneously at the end of the secondary 

 stage, while in others the infection lies latent or proceeds to 

 tertiary manifestations. There are no data available from 

 which even approximate percentages can be estimated. More- 

 over it is likely that the late manifestations of the disease vary 

 somewhat in different localities in the Tropics. In Santo 

 Domingo, large numbers of extremely bad cases of clavos were 

 seen. In Paranaque some effort was required to find clavos 

 cases, and the lesions were not extensive. 



The available clinical evidence indicates that the majority of 

 patients, after passing through the secondary stage, are not 

 likely in later years to experience a return of the typical 

 granulomatous eruption. Immunologically, distinction must be 

 made between a sterilizing immunity and a refractory latent 

 infection preventing reinfection. The treponemata of yaws 

 may behave, on the one hand, like the spirochsetes of relapsing 

 fever which many believe produce true immunity; or, on the 

 other hand, they may behave like the treponemata of syphilis. 

 These points have been investigated by the reinoculation of 

 yaws in one group of patients during the secondary stage of 

 the disease, and in another group some months after treatment 

 with neosalvarsan. The dosage was regulated according to the 

 table in the fourth paper of this series. These patients 

 cooperated cheerfully and faithfully in all of this work, and for 

 no recompense except the treatment with neosalvarsan which 

 they received. 



REINOCULATION OF YAWS PATIENTS DURING THE SECONDARY STAGE 



It was assumed, on clinical grounds, that patients in the 

 primary or the early secondary stage of the disease could be 

 readily reinfected with yaws. The secondary lesions do not 

 differ from the primary ones in any respect. Successive crops 

 appear from time to time in such patients for a period of many 



