Yaws is the most prevalent infectious, nonvenereal treponemal disease and is caused by Treponema pallidumpertenue. Yaws, endemic syphilis (bejel), and pinta collectively constitute the endemic treponematoses. Yaws is transmitted by direct skin contact and primarily affects children younger than 15 years, with a peak incidence in those aged 6-10 years. Similar to syphilis, yaws can persist for years as a chronic, relapsing disease.
Yaws continues to be endemic along the tropical belt in areas characterized by hot temperatures, high humidity, and heavy rainfall. These conditions, coupled with the persistence of poverty, poor sanitation, overcrowding, and lack of public health surveillance, allow for yaws perpetuation.
Between the years 1952 and 1964, the World Health (WHO) and UNICEF (United Nations Children’s Fund) undertook a major worldwide campaign to eliminate the endemic treponematoses by treating 300 million people in 46 countries with benzathine benzylpenicillin. They achieved a 95% success rate; however, there was a reemergence of yaws in the 1970s. In 1995, the WHO estimated that there were 460,000 infectious cases of yaws throughout the world, with 400,000 in western and central Africa, 50,000 in Southeast Asia, and the remainder in other tropical areas.
A new yaws eradication program was proposed in 2012 by the WHO following a study that showed that oral azithromycin can successfully treat yaws in rural, tropical areas. Compared to benzathine benzylpenicillin, oral azithromycin is a simpler regimen that does not require trained medical personnel for administration.
In India, yaws was successfully eradicated through a programm based on providing information to the population at risk, screening, and treatment. The WHO has concluded that this new eradication campaign can completely eliminate yaws worldwide by 2020.