Sensitive and semiquantitative detection of soil-transmitted helminth infection in stool using a recombinase polymerase amplification-based assay
Open Access
- 13 September 2021
- journal article
- research article
- Published by Public Library of Science (PLoS) in PLoS Neglected Tropical Diseases
- Vol. 15 (9), e0009782
- https://doi.org/10.1371/journal.pntd.0009782
Abstract
Soil-transmitted helminths (STHs) are parasitic nematodes that inhabit the human intestine. They affect more than 1.5 billion people worldwide, causing physical and cognitive impairment in children. The global strategy to control STH infection includes periodic mass drug administration (MDA) based on the results of diagnostic testing among populations at risk, but the current microscopy method for detecting infection has diminished sensitivity as the intensity of infection decreases. Thus, improved diagnostic tools are needed to support decision-making for STH control programs. We developed a nucleic acid amplification test based on recombinase polymerase amplification (RPA) technology to detect STH in stool. We designed primers and probes for each of the four STH species, optimized the assay, and then verified its performance using clinical stool samples. Each RPA assay was as sensitive as a real-time polymerase chain reaction (PCR) assay in detecting copies of cloned target DNA sequences. The RPA assay amplified the target in DNA extracted from human stool samples that were positive for STH based on the Kato-Katz method, with no cross-reactivity of the non-target genomic DNA. When tested with clinical stool samples from patients with infections of light, moderate, and heavy intensity, the RPA assays demonstrated performance comparable to that of real-time PCR, with better results than Kato-Katz. This new rapid, sensitive and field-deployable method for detecting STH infections can help STH control programs achieve their goals. Semi-quantitation of target by RPA assay is possible and is comparable to real-time PCR. With proper instrumentation, RPA assays can provide robust, semi-quantification of STH DNA targets as an alternative field-deployable indicator to counts of helminth eggs for assessing infection intensity. More than 1.5 billion people are infected with parasitic intestinal worms called soil-transmitted helminths. Infection is transmitted by helminth eggs in human feces, which contaminate soil in areas with poor sanitation. Adverse health effects include physical and cognitive impairment in children. A key strategy to control infection is periodic mass drug administration for populations with a high prevalence of disease based on the results of diagnostic testing. The current microscopy method for detecting infection, however, has limited ability to detect disease as the intensity of infection decreases with repeated mass drug administration. To address limitations of current diagnostic methods, we developed a novel technique to diagnose infections, including those at very low levels of intensity, by detecting helminth DNA in stool samples. Our initial studies suggest that the new diagnostic technique reliably detects the presence of intestinal worms, even at low intensities of infection, and may be more useful than currently available diagnostic tools for guiding the use of periodic mass drug administration to eliminate disease in low-resource settings.Keywords
Funding Information
- Department for International Development, UK Government (204139)
- Janssen Research and Development (AWD-345792)
- Bill and Melinda Gates Foundation (OPP1109096)
This publication has 60 references indexed in Scilit:
- An Extensive Comparison of the Effect of Anthelmintic Classes on Diverse NematodesPLOS ONE, 2013
- Discrimination of Gastrointestinal Nematode Eggs from Crude Fecal Egg Preparations by Inhibitor-Resistant Conventional and Real-Time PCRPLOS ONE, 2013
- A Research Agenda for Helminth Diseases of Humans: Diagnostics for Control and Elimination ProgrammesPLoS Neglected Tropical Diseases, 2012
- Are Ascaris lumbricoides and Ascaris suum a single species?Parasites & Vectors, 2012
- A stochastic model of the processes in PCR based amplification of STR DNA in forensic applicationsForensic Science International: Genetics, 2012
- A Pentaplex Real-Time Polymerase Chain Reaction Assay for Detection of Four Species of Soil-Transmitted HelminthsThe American Journal of Tropical Medicine and Hygiene, 2011
- Serious Overestimation in Quantitative PCR by Circular (Supercoiled) Plasmid Standard: Microalgal pcna as the Model GenePLOS ONE, 2010
- DNA supercoiling suppresses real-time PCR: a new approach to the quantification of mitochondrial DNA damage and repairNucleic Acids Research, 2007
- A Real-Time PCR Method for Quantifying Viable Ascaris Eggs Using the First Internally Transcribed Spacer Region of Ribosomal DNAApplied and Environmental Microbiology, 2006
- DNA Detection Using Recombination ProteinsPLoS Biology, 2006