Yaws is a bacterial infection caused by the spirochete Treponema pallidum, which is related to syphilis. It is characterized by skin lesions and can affect the bones and joints. The most common form of yaws is framboesia, which is a chronic skin infection that causes disfiguring nodules and ulcers. Pian is an acute form of yaws that is characterized by fever and joint pain. Frambesia is another form of yaws that is characterized by skin lesions and ulcers. Veers is a rare form of yaws that is characterized by fever, joint pain, and skin lesions.