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[From Carib yaya, sore]
A chronic, infectious tropical disease that affects skin, bones, and joints.

It is a common illness in school-aged children in tropical, resource-poor countries.

Yaws is caused by a spirochete, Treponema pallidum subspecies pertenue, a member of the same species of spirochetes that causes syphilis. The disease is spread by person-to-person contact when an infected lesion on the skin of one individual (or the clothing worn by that person) rubs against the skin of another. Despite its relationship with syphilis, the disease is not sexually transmitted.

During the initial phase of infection with yaws a large, painless, warty papule that resembles a strawberry forms on the skin at the inoculation site. This lesion (the “mother yaw”) heals, but after about a month of dissemination of treponema through blood vessels, multiple lesions appear elsewhere on the body, esp. near the mouth, nose, anus, and other mucus membranes. After these lesions heal, the disease may be quiescent for several years until it becomes clinically apparent again because of the destructive changes the infection has on cartilage, bones (osteoperiosititis) and, sometimes, other organs. Thickened lesions form on the soles of the feet. These may crack or ulcerate making it painful for patients to walk. Disfiguring oral and nasal deformities occur in some patients. The chronic deformities caused by yaws do not consistently resolve even after antibiotic therapy.

Darkfield microscopy of exudate swabbed from the skin is used to identify the spiral-shaped bacteria that cause yaws. Serological tests for syphilis are positive in patients with yaws (including the rapid plasma reagin RPR and VDRL tests).

International campaigns to eliminate the disease from African, Pacific, and South American countries were carried out in the mid-twentieth century and markedly reduced the incidence and prevalence of yaws. Some countries, including India, have eradicated the disease entirely through population-based treatment campaigns. Infectious disease experts recommend treating every child in a hyperendemic area to eradicate the disease.

The traditional treatment for yaws has consisted of injected benzathine penicillin. The disease can also be treated with one dose of orally administered azithromycin.

Close personal contacts and health care providers should avoid skin-to-skin contact with patients with yaws. Personal protective equipment including gloves and gowns should be worn when handling patients with skin sores of unknown etiology. Patients identified with primary yaws are treated with prescribed antibiotics. They can be reassured that treatment is effective in a high percentage of patients. Children who develop multiple skin sores after visiting tropical countries should be referred to infectious disease specialists for treatment.
SYN: SEE: bouba; SEE: frambesia; SEE: parangi; SEE: pian

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