Treponema pallidum manifestations
Top Right: Treponema pallidum pallidum - Venereal Syphilis
Top Left: Treponema pallidum pertenue - Gangosa (Yaws)
Bottom: Treponema pallidum pertenue - Frambosia (Yaws)
The spirochete Trepanoma pallidum has several subspecies that affect man, though only T. p. pallidum (syphilis) is transmitted via sexual contact. The other common disease caused by the spirochete is yaws. This tropical disease was largely ignored for most of the 20th century, as it rarely affects affluent countries.
Its course of infection can sometimes resemble syphilis, with the ulcerating gummas, multiple stages of infection, and destruction of tissues, but it is transmitted via skin-to-skin contact, and is not known to cross the placental membrane (meaning that, unlike syphilis, babies cannot be born with it). The tissue destruction within the muscles, skin, and bones, is a feature of tertiary yaws, which arises years after the initial infection. When the facial tissues are destroyed, the disease is commonly called gangosa.
[A Treatise on the Diseases of the Skin. Henry W. Stelwagon, 1923]
[Human Parasitology. Damaso Rivas, 1920.]