Characterization of the skeletal manifestations of the treponemal disease yaws as a population phenomenon.

Documentation of the antiquity and tracking of the derivation of human treponemal diseases have been complicated by an inability to distinguish among these diseases biochemically, histologically, and immunologically. Skeletal impact, as a population phenomenon, has been suspected to vary sufficiently among the treponemal disorders to allow their differentiation. As yaws was the only treponemal infection present in pre-Spanish Guam, definitive characterization of this disease in terms of its skeletal impact has been possible. In the studies described herein, skeletons from a 500-year-before-present archaeological site at Gognga-Gun Beach were examined. Yaws-related periostitis was noted in 19% of skeletons, achieving full population "penetrance" by the second decade of life. While the cortical-surface striations were often quite subtle, general osseous expansion and saber shin deformity were noted in one-fourth of skeletons. Gummatous destruction was found in 15% of individuals and draining cloacae in 10%. Invariably, the presence of irregular/striated cortical-surface markings (along with saber shin deformity) and the absence of epiphyseal separation or dental abnormalities distinguished the lesions of yaws from those of syphilis.