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The endemic treponematoses are chronic diseases that are transmitted by direct contact, usually during childhood and, like syphilis, can cause severe late manifestations years after initial infection. These diseases are caused by very close relatives of Treponema pallidum subspecies pallidum, the etiologic agent of venereal syphilis (Chap. 182). Yaws, pinta, and endemic syphilis (bejel) have traditionally been distinguished from venereal syphilis by mode of transmission, age of acquisition, geographic distribution, and clinical features; however, there is overlap for each of these factors. Our “knowledge” about these infections is based on observations by health care workers who have visited endemic areas during the past 70 years. Except for the ongoing programs of mass drug administration (MDA) for yaws eradication promoted by the World Health Organization (WHO), virtually no well-designed studies of the natural history, diagnosis, or treatment of these infections have been conducted. The classically defined treponemal infections are compared and contrasted in Table 183-1.

TABLE 183-1Comparison of the Treponemes and Associated Diseases


Generally, yaws flourishes in moist tropical areas (Fig. 183-1); endemic syphilis has been found primarily in arid climates of West Africa and the Middle East; and pinta has been found in temperate foci in the Americas. Because no recent epidemiologic data are available for bejel and pinta, the current extent of these infections as classically described is unknown. The endemic treponematoses have traditionally been limited to rural areas of developing nations and have been seen in developed countries primarily among recent immigrants from endemic regions.

FIGURE 183-1

Geographic distribution of yaws in 2016. *No data reported since 2008 (Timor Leste) or 2009 (Democratic Republic of Congo). (Adapted from 2016 data available at and ...

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