A comparison of the diagnostic capability of Kato-Katz and real-time PCR for the assessment of treatment efficacy of ivermectin and albendazole combination against T. trichiura infections

by Gabriela Matamoros, Ana Sanchez, Ruben Cimino, Alejandro Krolewiecki, Rojelio Mejia

Trichuris trichiura is humans’ second most prevalent soil-transmitted helminth (STH) infection after Ascaris lumbricoides, affecting approximately 4.6 million people worldwide. Despite its sub-optimal sensitivity, especially in low prevalence and infection intensity settings, the modified Kato-Katz (K-K) is still recommended as a diagnostic method by the World Health organization (WHO) guidelines.

Within a randomized clinical trial (RCT) comprising four treatment arms with two different anthelmintics, the present study reports an important secondary research objective to determine the diagnostic agreement between K-K and real-time PCR evaluating treatment efficacy against T. trichiura. The parasitological results were analyzed, including cure rates (CR) of a subgroup of 94 participants positive at baseline for T. trichiura eggs for both techniques. The single-dose albendazole (ALB) arm resulted in significantly lower CRs than experimental arms of albendazole/ivermectin (ALB/IVM) combinations. The overall diagnostic agreement between both techniques was 88.7% [κ = 0.8 (P<0.001)]. Concordance between eggs per gram and Ct values was moderate, with the discordance source likely stemming from lighter infection intensities.

These findings indicate that real-time PCR is a suitable alternative for CR estimation in helminthiasis clinical trials. It also highlights the need to identify the most accurate diagnostic tools for RCTs, that would benefit from guiding principles to achieve harmonization across studies and are not necessarily the same as those used for epidemiological surveys.

Clinical Trials.gov (NCT04041453)