High Quality Content by WIKIPEDIA articles! Yaws (also frambesia tropica, thymosis, polypapilloma tropicum, pian or parangi, "Bouba," "Frambösie," and "Pian") is a tropical infection of the skin, bones and joints caused by the spirochete bacterium Treponema pallidum pertenue. Other treponemal diseases are bejel (Treponema pallidum endemicum), pinta (Treponema pallidum carateum), and syphilis (Treponema pallidum pallidum).