Comprehensive evaluation of stool-based diagnostic methods and benzimidazole resistance markers to assess drug efficacy and detect the emergence of anthelmintic resistance: A Starworms study protocol

Abstract

BackgroundTo work towards reaching the WHO goal of eliminating soil-transmitted helminth (STH) infections as a public health problem, the total number of children receiving anthelmintic drugs has strongly increased over the past few years. However, as drug pressure levels rise, the development of anthelmintic drug resistance (AR) is more and more likely to appear. Currently, any global surveillance system to monitor drug efficacy and the emergence of possible AR is lacking. Consequently, it remains unclear to what extent the efficacy of drugs may have dropped and whether AR is already present. The overall aim of this study is to recommend the best diagnostic methods to monitor drug efficacy and molecular markers to assess the emergence of AR in STH control programs.MethodsA series of drug efficacy trials will be performed in four STH endemic countries with varying drug pressure (Ethiopia and Brazil: low drug pressure, Lao PDR: moderate drug pressure and Tanzania: high drug pressure). These trials are designed to assess the efficacy of a single oral dose of 400 mg albendazole (ALB) against STH infections in school-aged children (SAC) by microscopic (duplicate Kato-Katz thick smear, Mini-FLOTAC and FECPAKG2) and molecular stool-based diagnostic methods (quantitative PCR (qPCR)). Data will be collected on the cost of the materials used, as well as the time required to prepare and examine stool samples for the different diagnostic methods. Following qPCR, DNA samples will also be submitted for pyrosequencing to assess the presence and prevalence of single nucleotide polymorphisms (SNPs) in the β-tubulin gene. These SNPs are known to be linked to AR in animal STHs.DiscussionThe results obtained by these trials will provide robust evidence regarding the cost-efficiency and diagnostic performance of the different stool-based diagnostic methods for the assessment of drug efficacy in control programs. The assessment of associations between the frequency of SNPs in the β-tubulin gene and the history of drug pressure and drug efficacy will allow the validation of these SNPs as a marker for AR in human STHs.Trial registrationThe trial was retrospectively registered the 7th of March 2018 on Clinicaltrials.gov (ID: NCT03465488).

Impact of Different Sampling Schemes for Decision Making in Soil-Transmitted Helminthiasis Control Programs

“…Estimated are based on 10 000 bootstraps. (A) Ugandan dataset [5]; (B) Indian dataset [6]; (C) Kenyan data (TUMIKIA) [8,9]; (D) Tanzanian dataset (Starworms) [10][11][12].…”

“…The third dataset constituted baseline data from the TUMIKIA study, a cluster-randomized trial in 120 clusters of villages in Kenya [8,9], in which 1 individual per household was tested with duplicate KK based on a single stool sample. The fourth dataset contained baseline data from the Starworms study [10][11][12] in which school-age children in Ethiopia, Lao People's Democratic Republic, and Tanzania were tested using (among other techniques) duplicate KK performed on a single stool sample. The Starworms study was the only study in which stool samples were homogenized before preparing the fecal smears.…”

Pooling as a strategy for the timely diagnosis of soil-transmitted helminths in stool: value and reproducibility

“…4 The Hospital for Sick Children, Toronto, ON, Canada. 5 Molecular and Cellular Biology Programme, University of Massachusetts, Amherst, MA, USA. 6 Core Research Laboratories, Natural History Museum, London, UK.…”

“…Such tools would ideally retain their sensitivity when samples from multiple individuals are combined, whilst minimizing the reagent cost implicated. More recent studies report additional cost granularity, including operational and logistical costs, concluding that a 'pooling approach' might not be as worthwhile as hoped [5]. These studies, however, have neither taken into account predicted pool sizes as optimal nor have they incorporated an adequately sensitive diagnostic tool; thus, such conclusions are yet to be confirmed.…”

“…Pooling of faeces [1][2][3][4][5], urine [6,7], serum [8] or disease vectors [9] have all been used as a cost-effective strategy to screen for infection present in the given substrate/ matrix. Such an approach has been shown to provide accurate results, while reducing time and labour requirements.…”