This disease has suffered from variable and confusing descriptions. It is now generally called yaws, although the term framboesia is also still in common use. Although primary, secondary, and tertiary stages of the condition are recognized, further subdivisions have been made that are associated with various alternative terminology.

Yaws is generally considered to be a highly contagious disease in tropical areas of the world, and in populations with limited hygiene. It is characterized in the early stages by variable cutaneous changes, and eventually affects joints and bones. The causal organism is considered to be Treponema pertenue, although the taxonomy of the pathogenic treponemes is in some doubt, and some reclassification may well take place in the near future. An incubation period of up to 28 days is followed by the appearance of the primary lesion, 2 to 5 centimeters in diameter, which develops into granular excrescences at times with lymph node enlargement. Further eruptions take place, which can be characterized by a “waxing and waning” of successive lesions. Single or multiple lesions can eventually develop on the feet (“crab yaws,” “ulcerative plantar papules”) and are some of the most painful and disabling lesions of all. Eventually, in what some would see as a tertiary stage, there can be patchy depigmentation, deep destruction and remodeling of bones, and gangosa (changes to nasopharyngeal structures). The internal organs are not normally involved, and in this respect it contrasts markedly with the sister treponematosis venereal syphilis.