Yaws is a non-venereal endemic treponemal infection caused by Treponema pallidum sub-species pertenue, a bacterium closely related to Treponema pallidum ssp. pallidum, the agent of venereal syphilis. Yaws predominantly affects children living in tropical regions of the world. It causes lesions of the skin, mucous membranes and bones which, without treatment, can become chronic and destructive. There is no widely available test to distinguish yaws from syphilis. Thus, migration of people from yaws-endemic areas to developed countries may present clinicians with diagnostic dilemmas. The other endemic treponemal infections are bejel (endemic syphilis) caused by Treponema pallidum ssp. endemicum and pinta caused by Treponema carateum.