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A diagnostic test developed for syphilis and an easier treatment involving the oral antibiotic azithromycin could help to stamp out yaws, a neglected skin and bone disease that the WHO has slated for eradication by 2020, a meeting has heard.
Syphilis and yaws are the result of infection by different subspecies of the bacteria Treponema pallidum. They could therefore be detected using the same blood tests, experts at a WHO meeting on yaws eradication heard last month (20–22 March) in Geneva, Switzerland.
- A trial will assess whether a syphilis test can reliably detect yaws disease
- An oral antibiotic is confirmed as being as effective a treatment as current injection
- These tools could help the WHO meet its 2020 yaws eradication goal
The Dual Path Platform (DPP) test for syphilis, recently developed by US firm Chembio Diagnostics, could also help to detect yaws cases that are difficult to diagnose based only on clinical symptoms. It could also assist in the surveillance that will be needed for years after endemic communities are treated with antibiotics, the meeting heard.
The test is designed to be used in the field rather than in an often-distant lab — a major advance for a disease that is typically prevalent in poor, isolated rural settings in tropical areas.
"Yaws is a disease neglected even [among] neglected diseases," said Matthew Coldiron, a doctor with medical charity Médecins Sans Frontières, at the meeting.
According to the WHO, surveys are underway to assess yaws’ full extent, but the disease is currently known to be present in Indonesia and Timor-Leste in South-East Asia; Papua New Guinea, the Solomon Islands and Vanuatu in the Pacific region; and Benin, Cameroon, Central African Republic, Congo, Côte d’Ivoire, Democratic Republic of Congo, Ghana and Togo in Africa.
The WHO meeting was attended by representatives of almost all countries where yaws is known to be endemic. In several such countries, mapping of the disease will need to be completed before serious eradication efforts start, the meeting heard.
Experts hope that the DPP test can assist this process, but it will require field testing before it can be used for diagnosing yaws in the field.
A field trial due to start in Vanuatu next month (May) will aim to verify whether the tool can effectively detect yaws in children, those mainly affected by the disease.
If this is successful, the test will then be used to help evaluate the impact of azithromycin antibiotic treatment in a further study planned in the country, the meeting heard.
"This new test is just what we need in order to empower peripheral health workers to diagnose and treat yaws," said Jacob Kool, WHO Medical Officer at Vanuatu.
"In combination with the newly available oral azithromycin treatment, yaws control at the primary healthcare level will be greatly strengthened. I hope it will be enough to finally eradicate this disease."
The results of a trial comparing single dose oral azithromycin with a painful injection of a form of the antibiotic penicillin to treat yaws in Ghana were also presented at the meeting.
The trial showed that treatment with azithromycin cured children as effectively as an injection.
These findings confirm those reported last year from a similar study in Papua New Guinea.
"We are really happy about these results and we are now planning a wider pilot study to assess the impact of mass treatment of yaws using azithromycin in endemic areas," Cynthia Kwakye, medical director for the Ghana Health Service, who presented the trial results, told SciDev.Net.
There was only limited discussion at the WHO meeting about fundraising for the campaign to eradicate yaws and potential donors contacted so far have proven reluctant to allocate resources.
Yet Jean Jannin, at the WHO Department of Control of Neglected Tropical Diseases, said: "The most difficult thing, as has happened in the past for other disease-control or eradication campaigns, is to convince the first donor. Once that is done, others will easily follow".