A general framework to support cost-efficient fecal egg count methods and study design choices for large-scale STH deworming programs–monitoring of therapeutic drug efficacy as a case study

Luc E. Coffeng*, Johnny Vlaminck, Piet Cools, Matthew Denwood, Marco Albonico, Shaali M. Ame, Mio Ayana, Daniel Dana, Giuseppe Cringoli, Sake J. de Vlas, Alan Fenwick, Michael French, Adama Kazienga, Jennifer Keiser, Stefanie Knopp, Gemechu Leta, Leonardo F. Matoso, Maria P. Maurelli, Antonio Montresor, Greg MiramsZeleke Mekonnen, Rodrigo Corrêa-Oliveira, Simone A. Pinto, Laura Rinaldi, Somphou Sayasone, Peter Steinmann, Eurion Thomas, Jozef Vercruysse, Bruno Levecke*

*Corresponding author for this work

Research output: Contribution to journalArticleAcademicpeer-review

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Abstract

Background Soil-transmitted helminth (STH) control programs currently lack evidence-based recommendations for cost-efficient survey designs for monitoring and evaluation. Here, we present a framework to provide evidence-based recommendations, using a case study of therapeutic drug efficacy monitoring based on the examination of helminth eggs in stool. Methods We performed an in-depth analysis of the operational costs to process one stool sample for three diagnostic methods (Kato-Katz, Mini-FLOTAC and FECPAKG2). Next, we performed simulations to determine the probability of detecting a truly reduced therapeutic efficacy for different scenarios of STH species (Ascaris lumbricoides, Trichuris trichiura and hook-worms), pre-treatment infection levels, survey design (screen and select (SS); screen, select and retest (SSR) and no selection (NS)) and number of subjects enrolled (100– 5,000). Finally, we integrated the outcome of the cost assessment into the simulation study to estimate the total survey costs and determined the most cost-efficient survey design. Principal findings Kato-Katz allowed for both the highest sample throughput and the lowest cost per test, while FECPAKG2 required both the most laboratory time and was the most expensive. Counting of eggs accounted for 23% (FECPAKG2) or ≥80% (Kato-Katz and Mini-FLOTAC) of the total time-to-result. NS survey designs in combination with Kato-Katz were the most cost-efficient to assess therapeutic drug efficacy in all scenarios of STH species and endemicity. Conclusions/significance We confirm that Kato-Katz is the fecal egg counting method of choice for monitoring therapeutic drug efficacy, but that the survey design currently recommended by WHO (SS) should be updated. Our generic framework, which captures laboratory time and material costs, can be used to further support cost-efficient choices for other important surveys informing STH control programs. In addition, it can be used to explore the value of alternative diagnostic techniques, like automated egg counting, which may further reduce operational costs. Trial Registration ClinicalTrials.gov NCT03465488.

Original languageEnglish
Article numbere0011071
JournalPLoS Neglected Tropical Diseases
Volume17
Issue number5
DOIs
Publication statusPublished - 17 May 2023

Bibliographical note

Funding Information:
LEC acknowledges funding from the Dutch Research Council (NWO, grant 016. Veni.178.023). JV was financially supported through an International Coordination Action of the Flemish Research Foundation. This study and PC were financially supported by a grant from the Bill and Melinda Gates foundation (OPP1120972, PI is BL, www.starworms.org). The collection of the Ethiopian National Mapping data (which was overseen by GL) that were used to define endemicity scenarios was financially supported by the Schistosomiasis Control Initiative and the Partnership for Child Development, both based at Imperial College London, and by the Children’s Investment Fund Foundation, The End Neglected Diseases Fund, and UKAID-DFID. The funders had no role in study design, data collection and analysis, decision to publish, or preparation of the manuscript.

Publisher Copyright:
© 2023 Coffeng et al.

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