yaws

Yaws is a chronic bacterial infection of the skin, bones, and soft tissues caused by Treponema pallidum pertenue. It is one of the endemic treponematoses and is closely related to syphilis, but it is transmitted primarily through non-sexual skin-to-skin contact rather than sexual contact.

Epidemiology and transmission: Yaws occurs in warm, humid tropical regions. It is endemic in parts of Africa, Asia, the Pacific, and Latin America. The disease mainly affects children, with adults less frequently involved. Transmission occurs through contact with infectious skin lesions, often during daily activities.

Clinical features: The disease progresses in stages. The initial lesion, a papillomatous or ulcerative skin lesion at the site of inoculation, is highly infectious. Weeks to months later, secondary skin lesions, usually non-tender, may appear on other parts of the body. Untreated disease can lead to bone and joint involvement with periostitis and deformities, particularly of the legs.

Diagnosis: Diagnosis relies on clinical suspicion in endemic settings, supplemented by serologic testing. Treponemal tests (such as TP-PA or FTA-abs) and non-treponemal tests (RPR or VDRL) are used; results must be interpreted with epidemiology in mind. In some centers, PCR or dark-field microscopy can help distinguish yaws from venereal treponematoses.

Treatment and prevention: Treatment is effective with antibiotics. Benzathine penicillin G given as a single intramuscular dose is a common first-line regimen. Alternatives include a single oral dose of azithromycin; for penicillin allergy, doxycycline or tetracycline can be used. Close contacts should be evaluated and treated. Public health efforts focus on early detection, treatment to interrupt transmission, and surveillance in endemic regions. Mass drug administration campaigns have been implemented in some areas as part of eradication programs. There is currently no widely available vaccine.