Frambesia tropica
Key points
- Yaws is a chronic infection caused by the bacteria Treponema pallidum, subspecies pertenue, which primarily affects the skin, bones, and joints.
- Yaws is an infection caused by the spiral-shaped bacterium (spirochete) called Treponema pertenue.
- Signs and tests The diagnosis can be confirmed by examining a sample from a skin lesion under a special type of microscope (darkfield examination).
- The mainstay of treatment is a single dose of penicillin G.
Alternative names
Yaws
Definition
Yaws is a chronic infection caused by the bacteria Treponema pallidum, subspecies pertenue, which primarily affects the skin, bones, and joints.
Causes, incidence, and risk factors
Yaws is an infection caused by the spiral-shaped bacterium (spirochete) called Treponema pertenue. It is closely related to the organism that causes syphilis, but this disease is not sexually transmitted. Yaws mainly affects children in rural, warm, tropical areas - primarily Caribbean Islands, Latin America, West Africa, India, and Southeast Asia.
Yaws is transmitted by direct contact with skin lesions of infected people. Approximately two to four weeks after infection, the child develops a sore "mother yaw" where the organism entered the skin.
The sore appears as a "raspberry-like" growth or group of papules at the site of infection and is usually painless. These lesions may persist for months. Additional satellite lesions may appear shortly before or after the mother yaw heals. Children may also develop inflammation of the bones and fingers.
The final stage involves destructive lesions of the skin and bones which can lead to severe disfigurement and disability. It occurs in up to 20% of untreated individuals.
Symptoms
- Initial, single skin lesion that may grow slowly and have a raspberry-like appearance. It may also form an ulcer and is usually painless.
- Satellite lesions which may become large nodules/growths throughout the body and may have superficial erosions in secondary yaws.
- Fever may be present in secondary yaws.
- Bone pain/bone destruction; saber shins.
- Finger inflammation (dactylitis).
Signs and tests
The diagnosis can be confirmed by examining a sample from a skin lesion under a special type of microscope (darkfield examination). There is no specific blood test for yaws, but because it is closely related to the bacterium that causes syphilis, the blood tests for syphilis may be positive in yaws as well.
Treatment
The mainstay of treatment is a single dose of penicillin G. Relapse is rare.
Expectations (prognosis)
If appropriately treated in its early stages, yaws is highly curable. Skin lesions may take several months to heal. If treated in its late stage, significant disfigurement may already be present and may not be fully reversible.
Written and revised by
Andrey Nailor, M.D.
Our doctors write and review articles for accuracy and keep them up to date.
health.am provides general information, not medical advice. Always consult a qualified health professional about your own health.