Treatment is typically with antibiotics, including: azithromycin by mouth or benzathine penicillin by injection. Without treatment, physical deformities occur in 10% of cases.Yaws is common in at least 13 tropical countries as of 2012. Almost 85% of infections occurred in three countries—Ghana, Papua New Guinea, and Solomon Islands. The disease only infects humans. Efforts in the 1950s and 1960s by the World Health Organization  decreased the number of cases by 95%. Since then, cases have increased, but with renewed efforts to globally eradicate the disease by 2020. In 1995, the number of people infected was estimated at more than 500,000. In 2016, the number of reported cases was 59,000. Although one of the first descriptions of the disease was made in 1679 by Willem Piso, archaeological evidence suggests that yaws may have been present among human ancestors as far back as 1.6 million years ago. Signs and symptoms
Yaws is classified as primary, secondary, and tertiary; this is useful, but people often have a mix of stages.Within 9–90 days (but usually about 21 days) of infection, a painless but distinctive "mother yaw" nodule appears. Initially reddened and inflamed, it may become a papilloma, which can then become an ulcer, possibly with a yellow crust. Mother yaws are most commonly found on the legs and ankles, and are rarely found on the genitals (unlike syphilis) The mother yaw enlarges and becomes warty in appearance. Nearby "daughter yaws" may also appear simultaneously. This primary stage resolves completely, with scarring, within 3–6 months. The scar is often pigmented.
Treatment
Treatment is normally by a single intramuscular injection of long-acting benzathine benzylpenicillin, or less commonly by a course of other antibiotics, such as azithromycin or tetracycline tablets. Penicillin has been the front-line treatment since at least the 1960s, but there is no solid evidence of the evolution of penicillin resistance in yaws.The historical strategy for the eradication of yaws (1952–1964) was:
Benzathine benzylpenicillin requires a cold chain and staff who can inject it, and there is a small risk of anaphylaxis. It was also not reliably available during the 2010s; there have been supply shortages.In the 2010s, a single oral dose of azithromycin was shown to be as effective as intramuscular penicillin. Unlike penicillin, there is strong evidence that yaws is evolving antibiotic resistance to azithromycin; there are two known mutations in the bacterium, each of which can cause resistance and make the treatment ineffective. This has threatened eradication efforts.Within 8–10 hours of penicillin treatment, bacteria can no longer be found in lesion biopsies. Primary and secondary lesions usually heal in 2–4 weeks; bone pain may improve within two days. If treated early enough, bone deformities may reverse and heal. Primary and secondary stage lesions may heal completely, but the destructive changes of tertiary yaws are largely irreversible.If lesions do not heal, or RPR test results do not improve, this may indicate treatment failure or re-infection; the treatment is typically repeated. WHO guidelines says that any presumed treatment failures at 4 weeks require macrolide resistance testing.