Spirochete in the context of Periplasmic space

Yaws is a tropical infection of the skin, bones, and joints caused by the spirochete bacterium Treponema pallidum pertenue. The disease begins with a round, hard swelling of the skin, 2 to 5 cm (0.79 to 1.97 in) in diameter. The center may break open and form an ulcer. This initial skin lesion typically heals after 3–6 months. After weeks to years, joints and bones may become painful, fatigue may develop, and new skin lesions may appear. The skin of the palms of the hands and the soles of the feet may become thick and break open. The bones (especially those of the nose) may become misshapen. After 5 years or more, large areas of skin may die, leaving scars.

Yaws is spread by direct contact with the fluid from a lesion of an infected person. The contact is usually nonsexual. The disease is most common among children, who spread it by playing together. Other related treponemal diseases are bejel (T. pallidum endemicum), pinta (T. carateum), and syphilis (T. p. pallidum). The appearance of the lesions often diagnoses yaws. Blood antibody tests may be useful, but cannot separate previous from current infections. Polymerase chain reaction is the most accurate method of diagnosis.

Pinta (also known as azul, carate, empeines, lota, mal del pinto, and tina) is a human skin disease caused by infection with the spirochete Treponema carateum, which is morphologically and serologically indistinguishable from the bacterium that causes syphilis and bejel. The disease was previously known to be endemic to Mexico, Central America, and South America; it may have been eradicated since, with the latest case occurring in Brazil in 2020.

Treponema carateum is a species of spirochete bacteria in the genus Treponema.

It is the cause of pinta, a disease affecting exclusively the skin. Children living in tropical American countries are most at risk.

Bejel, or endemic syphilis, is a chronic skin and tissue disease caused by infection by the endemicum subspecies of the spirochete Treponema pallidum. Bejel is one of the "endemic treponematoses" (endemic infections caused by spiral-shaped bacteria called treponemes), a group that also includes yaws and pinta. Typically, endemic trepanematoses begin with localized lesions on the skin or mucous membranes. Pinta is limited to affecting the skin, whereas bejel and yaws are considered to be invasive because they can also cause disease in bone and other internal tissues.