A loop-mediated isothermal amplification test for yaws: a multi-country diagnostic accuracy evaluation

Area of Science:

• Tropical medicine
• Infectious diseases
• Molecular diagnostics

Background:

• The World Health Organization aims to eradicate yaws by 2030, necessitating advanced diagnostic tools.
• A multiplex Treponema pallidum-Haemophilus ducreyi loop-mediated isothermal amplification (TPHD-LAMP) test was developed for near-patient diagnosis of yaws and H. ducreyi.

Purpose of the Study:

• To evaluate the diagnostic accuracy, acceptability, feasibility, and cost of the TPHD-LAMP test in a multi-country setting.
• To assess the TPHD-LAMP test's performance against reference quantitative PCR (qPCR) for yaws detection.

Main Methods:

• Prospective evaluation in Cameroon, Côte d'Ivoire, Ghana, and Republic of the Congo.
• Inclusion of participants with clinically suspicious yaws-like lesions, confirmed by serology.
• Comparison of TPHD-LAMP test results with qPCR using paired lesion swabs.

Main Results:

• The TPHD-LAMP test demonstrated a sensitivity of 63% and specificity of 66% for T. pallidum detection.
• Improved sensitivity (73%) and specificity (75%) were observed in H. ducreyi-negative samples.
• User interviews revealed challenges with test user-friendliness and practicality, despite a lower per-sample cost than qPCR.

Conclusions:

• The TPHD-LAMP test, in its current iteration, does not meet the WHO's target product profile for yaws diagnostics.
• Real-world evaluations are crucial to ensure new diagnostic tools are suitable for programmatic use in disease eradication efforts.