Comparison of the standard Q syphilis antibody rapid diagnostic test to gold standards for yaws detection in children

Abstract

Introduction: Yaws remains a public health problem in Indonesia, and it is the largest contributor to Yaws cases in Southeast Asia. Yaws is caused by bacterial infection of Treponema pallidum subspecies pertenue, mainly affecting the skin and bones. An estimated 75% of new cases were found in children under 15. The diagnosis of yaws is based on clinical findings with serological confirmation. Rapid diagnostic tests (RDT) have been developed to diagnose Yaws faster and simpler and can thus be used in areas with limited resources.

Methodology: In this study, sensitivity and specificity of the solid phase immunochromatographic assay of Standard Q Syphilis Antibody (Ab) RDT was performed compared to Treponema Pallidum Haemagglutination Assay (TPHA Plasmatec®) and Rapid Plasma Reagin (RPR) in 195 children with yaws age 2-15 years in Halmahera Barat, Maluku.

Results: There were 116 children with clinical symptoms representative of yaws, but only 13 were serologically positive. The scar was the most commonly found lesion, and the most affected regions were the legs. The sensitivity and specificity of RDT compared to TPHA were 93.3% and 99.4%, respectively. The sensitivity and specificity of RDT compared to RPR were 100% and 98.4%, respectively.

Conclusions: Based on the excellent performance of this test, this study suggests that Standard Q Syphilis Ab RDT examination can be used as a screening test. However, unusual clinical findings, like scars in RDT reactive patients, indicated that RPR is still required to confirm the diagnosis of yaws.