Neglected tropical diseases

WHO renews efforts to achieve global eradication of yaws by 2020

Credit: C. Kwakye. Distribution of oral azithromycin during a yaws treatment campaign in Ghana, 2012
Single-dose oral antibiotic improves prospects for large-scale treatment of affected populations

19 October 2012 | Geneva

The World Health Organization (WHO) is providing technical support to 14 countries with persistent transmission of yaws or where the disease has re-emerged as part of a renewed effort to eradicate the disease. The WHO roadmap on neglected tropical diseases, published in January 2012, targets the eradication of yaws by 2020.

This renewed effort is warranted by the findings, published also in January 2012, of a study in Papua New Guinea showing that a single dose of oral azithromycin is as effective as a benzathine penicillin injection in curing the disease.

“This oral antibiotic makes it easier and more practical for health workers to administer treatment in remote areas where yaws occurs through large-scale treatment campaigns,” said Dr Oriol Mitjà of the Department of Medicine, Lihir Medical Center, Papua New Guinea, and author of the azithromycin study.

An oral route to cure yaws will overcome the operational and logistic constraints of the standard injection of benzathine penicillin, improving prospects for wider, rapid and large-scale interventions to treat entire affected communities/or individuals living in areas at risk.

In response to these developments, WHO convened a meeting of experts in Morges, Switzerland in March 2012 to develop a new strategy for the eradication of yaws. The new treatment policies of the Morges Strategy are:

  • Total community treatment: treatment of an entire endemic community for yaws irrespective of the number of clinical cases; and
  • Total targeted treatment: treatment of all active clinical cases and their contacts (involving household, school and playmates).

“The main aim of this new strategy is to ensure a more pragmatic and aggressive approach to dealing with all active and latent cases as well as all contacts, so that transmission can be interrupted in a reasonably short time," said Dr Kingsley Asiedu, Medical Officer in charge of WHO’s yaws eradication programme.

In 2007, reports of continued transmission and resurgence of the disease prompted WHO to include yaws in its list of neglected tropical diseases.

India success story

From 1996, India embarked on efforts to eliminate yaws and reported the final cases in 2003. After three consecutive years in which zero cases were reported, India declared interruption of yaws transmission in 2006. Up to 2011, zero cases have been reported, and careful serological surveys have revealed no evidence of transmission.

Past eradication efforts

Yaws and other endemic treponematoses were almost eradicated in the mid-1960s, after WHO and UNICEF jointly led a worldwide campaign in 46 countries between 1952 and 1964.

During this period, more than 300 million people were examined and about 50 million were treated with injectable penicillin. By 1964, the prevalence of the diseases had been reduced by almost 95%, making this joint WHO–UNICEF campaign one of the most remarkable success stories in public health.

However, premature integration of yaws and other endemic treponematoses activities into weak primary health-care systems, and the dismantling of the vertical eradication programmes after 1964, led to the failure to finish with the remaining 5% of cases. By the late 1970s, the diseases had resurged in a number of countries, particularly west Africa, prompting the World Health Assembly Resolution 31.58 on the Control of endemic treponematoses in 1978.

The disease

Yaws is a chronic bacterial infection caused by Treponema pallidum subsp. Pertenue an organism resembling that which causes venereal syphilis. The disease is found primarily in poor deprived communities in warm, humid and forest areas of Africa, Asia, Latin America and the Pacific. Poor socio-economic conditions facilitate the spread of yaws.

Humans are the main reservoir of infection and children bear the brunt of the disease. Yaws clinically presents as lesions of the skin, bone and cartilage. Without treatment, it can lead to gross deformities and disabilities. Yaws forms part of a group of infections caused by treponemes that include endemic syphilis (bejel) and pinta.

This group of infections is referred to as endemic treponematoses.