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What Is It?

Yaws is an infectious disease that affects the skin and bones. It's a tropical illness that was once common in West Africa, Indonesia, New Guinea, the Solomon Islands, Haiti, Dominica, Peru, Colombia, Ecuador and parts of Brazil. In these countries, yaws most often affects children between the ages of 2 and 5, especially children who wear few clothes, have frequent skin injuries and live in areas of poor hygiene.

During the 1950s, yaws was a common tropical illness, infecting 50 million to 100 million people. Since that time, the World Health Organization (WHO) has battled yaws in many tropical areas of the world. More than 160 million people have been examined in 46 countries, and more than 50 million cases of yaws have been treated with penicillin. As a result, the incidence of yaws declined dramatically worldwide. This disease always has been extremely rare in the United States.

Yaws is caused by a subspecies of Treponema pallidum, the bacterium that causes syphilis, a sexually transmitted disease. However, yaws is not transmitted sexually. Also, unlike syphilis, yaws does not have the potential to cause long-term damage to the heart and cardiovascular system. Yaws almost always is transmitted by direct contact with infected skin. Yaws has three stages:

  • Early yaws About three to five weeks after a person is exposed to yaws, a raspberrylike bump appears on the skin, commonly on the legs or buttocks. This bump, sometimes called a frambesioma or mother yaw, will gradually grow larger and form a thin yellow crust. The area can itch, and there can be swollen lymph nodes (swollen glands) nearby. The bump usually heals on its own within six months, and it often leaves a scar.

  • Second-stage yaws The next stage may begin while the mother yaw is still present, or it may not start until several weeks or months after the first stage of yaws heals. In this stage, a crusty rash forms, which can involve the face, arms, legs and buttocks. The bottoms of the feet also can become covered with painful, thick sores. If you get foot sores, walking can become painful and difficult, and you may resulting in a crablike gait called crab yaws. Although the bones and joints also can be affected, second-stage yaws usually does not cause destruction in these areas.

  • Late yaws Late yaws develops in only about 10% of people who are infected with yaws. It begins at least five years after early yaws starts, and it can cause severe damage to the skin, bones and joints, especially in the legs. Late yaws also can cause a form of facial disfiguration called gangosa or rhinopharyngitis mutilans as it attacks and destroys parts of the nose, upper jaw, palate (roof of mouth) and part of the throat called the pharynx. If there is swelling around the nose, a person with late yaws can have headaches, nasal discharge. The faces of people with late yaws often develop an appearance called goundou.

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From Health A-Z, Harvard Health Publications. Copyright 2007 by the President and Fellows of Harvard College. All rights reserved. Written permission is required to reproduce, in any manner, in whole or in part, the material contained herein. To make a reprint request, contact Harvard Health Publications. Used with permission of StayWell.

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