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Project Topic
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Yaws, caused by Treponema pallidum subsp pertenue (T. pallidum), is one of the neglected tropical diseases (NTDs) affecting millions of individuals in poor rural communities in Africa, Asia, and the Pacific Islands. It mostly affects children and can progress into severe bodily destruction. Recent developments using a single dose of oral azithromycin have renewed optimism that eradication can be achieved, contributing to the achievement of sustainable development goal 3 ‘ to end the epidemic of NTDs by 2030’. Diagnostics represent a major challenge for yaws eradication. Commonly used serological tests cannot differentiate current yaws from previous infection, nor differentiate yaws from other causes of similar skin lesions, such as Haemophilus ducreyi (H. ducreyi), both of which require the use of nucleic acid amplification tests (NAATs) for specific detection. The documented emergence of resistance to azithromycin makes clear the need for monitoring of drug resistance, using NAATs. Currently only a small number of research laboratories, distant from endemic settings, have capacity to run NAATs for yaws. There is a need for an accurate point-of-care NAAT assay to enable early detection and effective treatment of yaws and track progress towards eradication. We propose to evaluate rapid and simple NAAT-based loop-mediated isothermal amplification (LAMP) assays, which have demonstrated good performance in laboratory settings, for detection of T. pallidum and H. ducreyi. The overarching aim of this study is to validate the LAMP test for yaws diagnosis in endemic countries. The primary objective is to compare the performance of this LAMP test performed at the district level with the gold standard, a real-time quantitative polymerase chain reaction (qPCR) assay, performed at a national reference laboratory. As secondary objectives, we will provide an external quality assurance programme, evaluate the acceptability and cost of the assay, build national capacity in diagnostics and surveillance for azithromycin resistance, and evaluate further improvements to the LAMP assay. This will be a multi-country clinical evaluation trial with sites in Ghana, Cote d’Ivoire and Cameroon. These three countries report more than 15,000 cases of yaws annually and have been identified as priority countries for the ongoing WHO Yaws Eradication campaign. Existing research partnerships on yaws between European partners and these countries strengthen the platform for our current proposal. We expect the outcome of this proposal will result in WHO’s implementation of the LAMP test for yaws as one of the key reference diagnostic tests in yaws eradication and post-eradication surveillance.
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