热带肉芽肿（Yaws）也称为雅司病，是发生在皮肤、骨骼及关节的热带感染病，病原是螺旋体门的细菌梅毒螺旋体。热带肉芽肿一开始会在皮肤产生圆形的硬肿，直径约二至五公分，之后会破皮，变成溃疡，初期的皮肤损害会在三至六个月后会治愈 。在数周至一年后，关节及骨头会开始疼痛，会觉得疲倦，也会有新的皮肤损害。手掌及脚掌的皮肤会变厚及破裂。骨头（尤其是鼻子）可能会畸形 。五年后会有大规模的皮肤坏死及随之出现的疤痕。

热带肉芽肿的传播是透过直接接触感染病患身上创口的液体，且多半不是因性接触而感染 。此疾病最常见于孩童，因一起玩乐而传播。其余和梅毒螺旋体有关的疾病还有贝耶病（Treponema pallidum endemicum）、品他病 （Treponema pallidum carateum）及梅毒（Treponema pallidum pallidum）。热带肉芽肿常因外貌上的病变而被诊断出来。血液抗体检测可能有用，但没法区分是以前的感染或是新的感染。聚合酶链锁反应（简称PCR）是最精准的诊断方法。

Yaws (also known as frambesia tropica, thymosis, polypapilloma tropicum, parangi, bouba, frambösie, and pian) 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 centimeters in diameter. The center may break open and form an ulcer. This initial skin lesion typically heals after three to six 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 five years or more large areas of skin death with subsequent scarring may occur.