TY - JOUR KW - Diagnostic test KW - Yaws KW - Case detection AU - Handley BL AU - Gonzalez-Beiras C AU - Tchatchouang S AU - Hugues KA AU - Basing LA AU - Sylla A AU - Kouamé-Sina MS AU - Amanor I AU - Ndzomo P AU - Aloumba A AU - Bakheit M AU - Müller C AU - Borst N AU - Landmann E AU - Gmoser H AU - Härpfer T AU - Becherer L AU - Lüert S AU - Frischmann S AU - Burl S AU - Tabah EN AU - Crucitti T AU - Kouadio AT AU - Arhinful DK AU - Awondo P AU - Kakou SN AU - Eyangoh S AU - Addo KK AU - Knauf S AU - Mitjà O AU - Harding-Esch EM AU - Marks M AB -

Background: To meet the WHO target of eradicating yaws by 2030, highly sensitive and specific diagnostic tools are needed. A multiplex Treponema pallidumHaemophilus ducreyi loop-mediated isothermal amplification (TPHD-LAMP) test holds promise as a near-patient diagnostic tool for yaws and H ducreyi. We conducted a prospective evaluation in Cameroon, Côte d’Ivoire, Ghana, and the Republic of the Congo to determine the diagnostic accuracy of the TPHD-LAMP test, as well as to assess its acceptability, feasibility, and cost.

Methods: Active case searching within schools and communities was used to locate participants with clinically suspicious laws-like lesions. Individuals with serologically confirmed active yaws provided paired lesion swabs between March, 2021, and April, 2023. For each participant, one swab was tested with the TPHD-LAMP at a local district laboratory and the other with reference quantitative PCR (qPCR) tests conducted at national reference laboratories. The primary outcome was TPHD-LAMP test sensitivity and specificity compared with qPCR. Laboratory technicians were interviewed using a multiple-choice survey to gauge acceptability and feasibility of the TPHD-LAMP test. Costs of each test were calculated.

Findings: Of 3085 individuals with at least one suspected yaws lesion, 531 (17%) were serologically confirmed. We enrolled 493 participants with seropositive yaws and a further 32 with negative serology. The sensitivity of the TPHD-LAMP test for detecting T pallidum was 63% (95% CI 56–70) and the specificity was 66% (95% CI 61–71). Sensitivity and specificity for T pallidum improved to 73% (63–82; p=0·0065) and 75% (68–80; p=0·0003), respectively, in H ducreyi-negative samples. Interviews highlighted challenges in user-friendliness and practicality of the TPHD-LAMP test. The cost of the test per sample was one third of that of qPCR, although the TPHD-LAMP test entailed higher costs to establish the assay.

Interpretation: This was the first multi-country diagnostic evaluation of a molecular test for yaws. The TPHD-LAMP testing, in its current form, falls short of the WHO target product profile criteria for yaws diagnostics. These findings highlight the importance of assessing new diagnostics in real-world conditions to ensure their suitability for programmatic use.

BT - The Lancet Global Health DO - 10.1016/s2214-109x(24)00324-3 IS - 11 LA - ENG M3 - Article N2 -

Background: To meet the WHO target of eradicating yaws by 2030, highly sensitive and specific diagnostic tools are needed. A multiplex Treponema pallidumHaemophilus ducreyi loop-mediated isothermal amplification (TPHD-LAMP) test holds promise as a near-patient diagnostic tool for yaws and H ducreyi. We conducted a prospective evaluation in Cameroon, Côte d’Ivoire, Ghana, and the Republic of the Congo to determine the diagnostic accuracy of the TPHD-LAMP test, as well as to assess its acceptability, feasibility, and cost.

Methods: Active case searching within schools and communities was used to locate participants with clinically suspicious laws-like lesions. Individuals with serologically confirmed active yaws provided paired lesion swabs between March, 2021, and April, 2023. For each participant, one swab was tested with the TPHD-LAMP at a local district laboratory and the other with reference quantitative PCR (qPCR) tests conducted at national reference laboratories. The primary outcome was TPHD-LAMP test sensitivity and specificity compared with qPCR. Laboratory technicians were interviewed using a multiple-choice survey to gauge acceptability and feasibility of the TPHD-LAMP test. Costs of each test were calculated.

Findings: Of 3085 individuals with at least one suspected yaws lesion, 531 (17%) were serologically confirmed. We enrolled 493 participants with seropositive yaws and a further 32 with negative serology. The sensitivity of the TPHD-LAMP test for detecting T pallidum was 63% (95% CI 56–70) and the specificity was 66% (95% CI 61–71). Sensitivity and specificity for T pallidum improved to 73% (63–82; p=0·0065) and 75% (68–80; p=0·0003), respectively, in H ducreyi-negative samples. Interviews highlighted challenges in user-friendliness and practicality of the TPHD-LAMP test. The cost of the test per sample was one third of that of qPCR, although the TPHD-LAMP test entailed higher costs to establish the assay.

Interpretation: This was the first multi-country diagnostic evaluation of a molecular test for yaws. The TPHD-LAMP testing, in its current form, falls short of the WHO target product profile criteria for yaws diagnostics. These findings highlight the importance of assessing new diagnostics in real-world conditions to ensure their suitability for programmatic use.

PB - Elsevier BV PY - 2024 SP - e1891 EP - e1898 T2 - The Lancet Global Health TI - A loop-mediated isothermal amplification test for yaws: a multi-country diagnostic accuracy evaluation UR - https://www.thelancet.com/action/showPdf?pii=S2214-109X%2824%2900324-3 VL - 12 SN - 2214-109X ER -