ADVANCING STRATEGIES FOR

Yaws Eradication

Our work in Papua New Guinea has led to the identification of an affordable treatment against yaws that has placed this poverty-related disease on the verge of eradication.

What is Yaws

Yaws is a neglected tropical disease caused by the bacteria Treponema pallidum pertenue. Each year it affects more than 100,000 children between the ages of 5 and 15 in 13 endemic countries of West Africa, Southeast Asia, and the Pacific. It manifests in the form of painful ulcers on the skin, which are also a means of contagion of the disease. To prevent its spread, affected children cannot go to school or play with other children. Therefore, in addition to its physical impact, yaws causes stigma and economic sequelae, since the loss of months (or even years) of schooling limits the chances of those suffering from the disease to overcome poverty.

In advanced stages, yaws consumes the cartilages, causing disfiguration, and can affect the bones, generating irreversible disabilities. The disease challenges the development of entire communities, as adults who become disabled become an economic burden for their environment. Yaws reveals the existence of a circle between disease and poverty, according to which both components feed each other.

Neglected Tropical Diseases

The World Health Organization (WHO) has made a list of 18 diseases defined as “tropical” and “neglected”. It means that these pathologies affect people living in rural environments in tropical and subtropical countries. The affected populations live in conditions that favour the emergence or spread of diseases (lack of access to drinking water or sanitation, overcrowding, proximity to domestic animals and livestock…). In addition, these people do not have the resources to pay for a treatment, nor the ability to demand that governments take care of it. This makes them forgetful and excludes them from a system of research and innovation strongly determined by the market logic. In total, neglected tropical diseases affect more than 1 billion people each year.

If it affected people with purchasing power, yaws, along with other neglected tropical diseases, would already be eradicated.

Our Discovery

A game-changer to defeat Yaws

Until recently, the only treatment for yaws was injected penicillin. It requires several components (syringes, needles, plastic gloves, water…) that makes the administration very challenging in remote areas. In addition, only qualified personnel, who do not abound in yaws endemic areas, can administer the injections. Also, it is a painful treatment, which makes it difficult to apply to children.

In 2012, Dr. Oriol Mitjà discovered that a single dose of azithromycin eliminates the disease in a quick, painless, and affordable manner. Azithromycin is an antibiotic used for infections of the respiratory tract, very common in our pharmacies. The cost of this new treatment is one euro per person, which includes the purchase of the antibiotic and its distribution.

In parallel, Oriol Mitjà established a diagnostic method that allows to easily and quickly identify the presence of the bacteria that causes the disease.

The research led by Dr. Mitjà stimulated the World Health Organization (WHO) to launch a campaign to eradicate yaws, which makes it the candidate to become the second human disease ever eradicated from the planet (after smallpox). The global eradication effort, now underway, is expected to succeed in 2030.

Research on Tropical Cutaneous Ulcers and H. Ducreyi2

Traditionally, and due to lack of molecular confirmation tests in rural areas, all tropical Cutaneous Ulcers (CU) have been diagnosed as yaws, but recent research has shown that several pathogens can cause CU disease. Of particular importance has been the recent discovery of H. ducreyi as an agent of the condition.

After that discovery, our team has undergone numerous studies to understand more about this pathogen:

Our study published in 2018 (Gonzalez-Beiras et al., 2016) concluded that up to 60% of CU clinically diagnosed as yaws are in fact caused by H. ducreyi, and that these ulcers are also affecting mostly children in remote communities of the South Pacific and West Africa.
Treatment with azithromycin is the cornerstone of the yaws elimination campaign, and so we further provided definite clinical data on the efficacy of azithromycin to treat H. ducreyi CU (>95% healed) (Gonzalez-Beiras et al., 2017).
Regardless of these results, MDA campaigns with azithromycin do not seem to have a long-term effect on the prevalence of H. ducreyi ulcers, and therefore we performed several studies on H. ducreyi dynamic of transmission, the impact of MDA on different strains (3) and its potential environmental reservoir (Houinei et al., 2017).

New strategies to control H. ducreyi along with yaws need to be explored. Syndromic care for ulcers using azithromycin and multiple rounds of MDA could be included in future interventions of the Morges Strategy for yaws eradication. Mathematical modelling has shown the value of multiple rounds of MDA to reduce T. p. pertenue infection, and this could, in parallel, reduce H. ducreyi infection and potentially skin carriage.

LAMP4Yaws

The LAMP4Yaws is a study funded by the European and Developing Countries Clinical Trials Partnership (EDCTP) aimed at performing a diagnostic evaluation of the Treponema pallidum, Haemophilus ducreyi loop mediated isothermal test (TPHD-LAMP) for yaws. Additional multidisciplinary sub-studies will aid our understanding of yaws epidemiology and transmission and assess the feasibility and cost-effectiveness of the TPHD-LAMP assay for use in yaws eradication campaigns and national surveillance programmes.

The LAMP4Yaws is a collaboration between the following partners:

Coordination: London School for Hygiene and Tropical Medicine, UK
Field implementation: FLS, Spain
LAMP development and evaluation
- Federal Research Institute for Animal Health (FLI) , Germany
- Albert-Ludwigs-Universität Freiburg, Germany
- MAST diagnostics, Germany
And the collaborating partiers in the field where activities will take place:
- Centre Pasteur du Cameroun, Germany.
- Institut Pasteur de Cote D’Ivoire, Ivory Coast
- University of Ghana, Noguchi Memorial Institute for Medical Research, Ghana

In this multi-country, groundbreaking program, Dr. Camila G- Beiras, yaws and NTDs researcher from the Skin NTD/STI unit, coordinates the implementation of this project from the field in Cameroon, Ghana and Ivory Coast, including the implementation of the multi-country case searches and epidemiological analysis, and the deployment of capacity-building activities aimed at strengthening the countries’ capacity for conducting high quality clinical research.

We hope that the LAMP4Yaws study will ultimately result in WHO’s implementation of the TPHD-LAMP test for yaws as one of the key diagnostic tests in yaws eradication and post-eradication surveillance.

For further information, visit the project’s website.

Where the Roads End – documentary

“Where the roads end” is a documentary that tells the story of Oriol Mitjà and his fight against yaws disease. The film accompanies the researcher from the Fight Against AIDS Fundation (FLSIDA) during his day-to-day life on the remote island of Lihir in Papua New Guinea. Dr. Mitjà explains the process that allowed him to find a new treatment against a neglected disease of the skin that even he did not know before arriving at the island: yaws. The film also shows how, three years after the publication of his finding, the World Health Organization (WHO) is launching a campaign to eradicate the disease worldwide.

“Where the roads end” is directed by Noemí Cuní (Broadcaster Group) and co-produced by TV3 and Televisión Española under the impulse of the Obra Social “la Caixa”. The film owes its title to an old African saying: “Yaws begins where the roads end”. Watch the full documentary at the TV3 website.

Teaser

Selected Publications

Millat-Martínez, P; Katusele, M; Kasian, B; Omera, E; Jamea, E; Lorry, L (…); Baró, B.

Human and entomological determinants of malaria transmission in the Lihir Islands of Papua New Guinea: A cross-sectional study Journal Article

In: PLOS Neglected Tropical Diseases, vol. 19, iss. 1, 2025.