Medical Definition of Yaws
Yaws: A chronic infectious disease that occurs commonly in the warm, humid regions of the tropics. Yaws is characterized by bumps on the skin of the face, hands, feet, and genital area. Almost all cases of yaws are in children under 15 years of age. The organism that causes yaws is a type of spirochete bacteria, Treponema pertenue, which enters the skin at a scraped or cut spot after contact with an infected person. A painless bump (the mother yaw) arises and grows at this spot. Nearby lymph nodes may become swollen. The mother yaw is followed by recurring (secondary) crops of bumps and more swollen lymph nodes. In its late (tertiary) stage, yaws can destroy and deform areas of the skin, bones, and joints. The palms and soles tend to become thickened and painful ('dry crab yaws'). Diagnosis is confirmed via blood tests and via
dark-field examination of the spirochete under a microscope. Treatment involves administration of antibiotics. Also known as granuloma tropicum, polypapilloma tropicum, and thymiosis.
Last Editorial Review: 6/9/2016