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Yaws is a chronic illness which first affects the skin, and then affects the bones.


Yaws tends to strike children, particularly between the ages of two and five. It is common in areas where poverty and overcrowding interfere with good hygiene practices. The most common locations are in rural areas throughout Africa, Southeast Asia, and in locations bordering the equator in the Americas.

Causes and symptoms

Yaws is caused by a spiral-shaped bacterium (spirochete) called Treponema pertenue. This bacterium belongs to the same family as the bacterium that causes syphilis.
Yaws is passed among people by direct skin contact. It requires some kind of a scratched or insect bitten area in order for the bacteria to actually settle in and cause infection. An injured spot on the leg is the most common part of the body through which the bacteria enter. Young children, who are constantly bumping themselves in play, who wear little clothing, who do not wash their hands often, and who may frequently put their hands in their mouths, are particularly susceptible.
The first symptom of yaws occurs three to four weeks after acquiring the bacteria. The area where the bacteria originally entered the skin becomes a noticeable bump (papule). The papule grows larger and develops a punched-out center (ulcer), covered with a yellow crust. Lymph nodes in the area may become swollen and tender. This first papule may take as long as six months to heal. Secondary soft, gummy growths then appear on the face, arms and legs, and buttocks. These soft, tumor-like masses may grow on the soles of the feet, causing the patient to walk in an odd and characteristic fashion on the sides of his or her feet (nicknamed "crab yaws"). More destructive tumors may then disrupt the bones of the face, the jaw, and the lower leg. Ulcers around the nose and on the face may be very mutilating.


Samples taken from the first papules may be examined using a technique called dark-field microscopy. This often allows the spirochetes to be identified. They may also be identified in fluid withdrawn from swollen lymph nodes. Various tests can also be run on blood samples to determine if an individual is producing antibodies (special immune cells) which are specifically made in response to the presence of these spirochetes.


A single penicillin injection in a muscle is sufficient to completely end the disease.


Without treatment, yaws is a terribly disfiguring chronic illness. With appropriate treatment, the progression of the disease can be completely halted.


For a time, the World Health Organization (WHO) was working to totally eradicate yaws, just as smallpox was successfully eradicated. This has not occurred, however. WHO continues to work to identify and respond to outbreaks quickly, in an effort to at least slow the spread of yaws.



Centers for Disease Control and Prevention. 1600 Clifton Rd., NE, Atlanta, GA 30333. (800) 311-3435, (404) 639-3311. http://www.cdc.gov.

Key terms

Papule — A raised bump on the skin.
Ulcer — A punched-out, irritated pit on the skin.
Gale Encyclopedia of Medicine. Copyright 2008 The Gale Group, Inc. All rights reserved.


a highly infectious disease caused by the spirochete Treponema pertenue. It was once common in tropical and subtropical regions of the world such as equatorial Africa, Central and South America, the Caribbean, and Indonesia and nearby islands. However, programs of the World Health Organization have now reduced its incidence. Called also frambesia.
Transmission and Symptoms. Yaws is transmitted by direct contact. The first symptom, appearing usually about a month after exposure, is a single granulomatous lesion, an inflammatory but painless elevation of the skin. Called the “mother yaw,” this soon ulcerates. Open, oozing sores appear a few weeks later on the hands, feet, face, scalp, and trunk. Eventually, after several years, the disease causes tissue destruction, bone changes, and shortening of the fingers or toes, in a cycle that has a resemblance to leprosy and is sometimes mistaken for it.

The causative organism of yaws is closely related to that of syphilis, and both diseases give a positive result on the wassermann test. However, yaws is not primarily spread by coitus and is not classified as a sexually transmitted disease.
Treatment and Prevention. Effective treatment is by antibiotics, particularly penicillin. Unsanitary living conditions help spread the disease, and public health initiatives are ongoing.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.


An infectious tropical disease caused by Treponema pertenue and characterized by the development of crusted granulomatous ulcers on the extremities; may involve bone, but, unlike syphilis, does not produce central nervous system or cardiovascular pathology.
See also: nonvenereal syphilis.
[of Caribbean origin; similar to Calinago yaya, the disease]
Farlex Partner Medical Dictionary © Farlex 2012


pl.n. (used with a sing. or pl. verb)
A highly contagious tropical disease that chiefly affects children, caused by the spirochete Treponema pertenue and characterized by raspberrylike sores, especially on the hands, feet, and face. Also called frambesia.
The American Heritage® Medical Dictionary Copyright © 2007, 2004 by Houghton Mifflin Company. Published by Houghton Mifflin Company. All rights reserved.


An infectious tropical disease caused by Treponema pertenue and characterized by the development of crusted granulomatous ulcers on the extremities; may involve bone, but, unlike syphilis, does not cause central nervous system or cardiovascular damage.
Synonym(s): boubas, bubas, frambesia, granuloma tropicum, pian, rupia (2) .
[of Caribbean origin; similar to Calinago word yaya, the disease]
Medical Dictionary for the Health Professions and Nursing © Farlex 2012


A disease of underdeveloped areas caused by a SPIROCHAETE of the genus Treponema identical to that causing SYPHILIS. Yaws is not, however, a sexually transmitted disease. It is acquired in childhood and is spread by direct contact. Initially, an itchy, red, warty patch appears at the site of infection. This is teeming with spirochaetes and scratching leads to further patches arising elsewhere on the skin. These, and secondarily appearing patches, heal, but, as in syphilis, a more serious tertiary stage occurs several years later. This features deep skin ulcers with much tissue destruction, bone changes and leprosy-like deformity. Yaws is easily treated with antibiotics such as penicillin or tetracycline. Mass treatment campaigns have been effective but have been followed by a sharp rise in the incidence of venereal syphilis, possibly reflecting a general decline in immunity.
Collins Dictionary of Medicine © Robert M. Youngson 2004, 2005


M., 19th century Dutch army surgeon in Java.
Charlouis disease - an infectious tropical disease caused by Treponema pertenue and characterized by the development of crusted granulomatous ulcers on the extremities. Synonym(s): yaws
Medical Eponyms © Farlex 2012


Infectious disease caused by Treponema pertenue and characterized by development of crusted granulomatous ulcers on extremities; may involve bone, but, unlike syphilis, does not affect central nervous or cardiovascular pathology systems.
[of Caribbean origin; similar to Calinago word yaya, the disease]
Medical Dictionary for the Dental Professions © Farlex 2012
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