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Yaws

Frambesia tropica

Definition

Yaws is a long-term (chronic) bacterial infection that mainly affects the skin, bones, and joints.

Causes

Yaws is an infection caused by a form of the Treponema pallidum bacteria. It is closely related to the bacterium that causes syphilis, but this form of the bacterium is not sexually transmitted. Yaws mainly affects children in rural, warm, tropical areas, such as, Africa, Western Pacific islands, and Southeast Asia.

Yaws is transmitted by direct contact with the skin sores of infected people.

Symptoms

About 2 to 4 weeks after infection, the person develops a sore called a "mother yaw" where bacteria enter the skin. The sore may be tan or reddish and looks like a raspberry. It is most often painless, but does cause itching.

The sores may last for months. More sores may appear shortly before or after the mother yaw heals. Scratching the sore can spread the bacteria from the mother yaw to uninfected skin. Eventually, the skin sores heal.

Other symptoms include:

Bone pain
Scarring of the skin
Swelling of the bones and fingers

In the advanced stage, sores on the skin and bones can lead to severe disfigurement and disability. This occurs in up to 1 in 5 people who do not get antibiotic treatment.

Exams and Tests

A sample from a skin sore is examined under a special type of microscope (darkfield examination).

There is no blood test for yaws. However, the blood test for syphilis is often positive in people with yaws because the bacteria that cause these two conditions are closely related.

Treatment

Treatment involves a single dose of penicillin, or 3 weekly doses for later stage disease. It is rare for the disease to return.

People who live in the same house with someone who is infected should be examined for yaws and treated if they are infected.

Outlook (Prognosis)

If treated in its early stages, yaws can be cured. Skin lesions may take several months to heal.

By its late stage, yaws may have already caused damage to the skin and bones. It may not be fully reversible, even with treatment.

Possible Complications

Yaws may damage the skin and bones. It can affect a person's appearance and ability to move. It can also cause deformities of the legs, nose, palate, and upper jaw.

When to Contact a Medical Professional

Contact your health care provider if:

You or your child has sores on the skin or bone that don't go away.
You have stayed in tropical areas where yaws is known to occur.

References

Dionne JA, Ghanem KG. Syphilis and nonsyphilitic treponematoses. In: Goldman L, Cooney KA, eds. Goldman-Cecil Medicine. 27th ed. Philadelphia, PA: Elsevier; 2024:chap 295.

Obaro SK, Davies HD. Nonvenereal treponemal infections. In: Kliegman RM, St. Geme JW, Blum NJ, et al, eds. Nelson Textbook of Pediatrics. 22nd ed. Philadelphia, PA: Elsevier; 2025:chap 265.

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Review Date: 12/31/2023

Reviewed By: Jatin M. Vyas, MD, PhD, Associate Professor in Medicine, Harvard Medical School; Associate in Medicine, Division of Infectious Disease, Department of Medicine, Massachusetts General Hospital, Boston, MA. Also reviewed by David C. Dugdale, MD, Medical Director, Brenda Conaway, Editorial Director, and the A.D.A.M. Editorial team.

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