Evaluating the yaws diagnostic gap: a survey to determine the capacity of and barriers to improving diagnostics in all yaws-endemic countries

Abstract

BackgroundYaws, caused by Treponema pallidum subsp. pertenue, is a skin neglected tropical disease. It is targeted for eradication by 2030, primarily using mass drug administration (MDA) with azithromycin. Traditionally, diagnosis of yaws has relied on clinical examination and serological testing. However, these approaches have poor diagnostic performance. To achieve eradication, more accurate diagnostics are required to determine whether MDA should be initiated or continued as well as for post-elimination surveillance. Molecular tools will be crucial for detecting antimicrobial resistant cases, which have the potential to derail eradication efforts. In order to determine the feasibility of introducing novel, more accurate, diagnostics for yaws surveillance purposes, it is necessary to understand current in-country diagnostic capacity. This study therefore aimed to understand the current capacity of, and challenges to, improving diagnostics for yaws in all yaws-endemic countries worldwide.Methodology/ principal findingsAn online survey was sent to all 15 yaws-endemic countries in July 2021. The survey asked about past prevalence estimates, the availability of different diagnostic tools, and perceived barriers to enhancing capacity. Fourteen countries responded to the survey, four of which did not have a current National Policy for yaws eradication in place. Over 95% of reported that yaws cases from the past five years had not been confirmed with serological or molecular tools, largely due to the limited supply of rapid serological tests. Only four countries reported having operational laboratories for molecular yaws diagnosis, with only one of these having a validated assay to detect azithromycin resistance.Conclusions and SignificanceThis study highlights the diagnostic capacity constraints across all respondent countries. Countries are in need of access to a sustainable supply of serological tests, and development of molecular testing facilities. Sufficient sustainable funding should be made available to ensure that appropriate diagnostic tools are available and utilised.

Finding Yaws among Indigenous People: Lessons from Case Detection Surveys in Luzon and Visayas Island Groups of the Philippines

“…We could not perform PCR confirmation of the etiologic agent of active yaws skin lesions due to the lack of PCR facilities within the Philippines and a budget to send specimens to laboratories abroad. The funds and diagnostic capacity for PCR confirmation of yaws are generally lacking, as reported by Handley et al 24 in a recent survey of yawsendemic countries, including the Philippines. Ideally, PCR to confirm T. pallidum pertenue would have to be performed on yaws-like skin ulcers among children because concomitant infection caused by Hemophilus ducreyii is also possible.…”