Multi-parallel quantitative real-time PCR based diagnostics as the new gold standard for soil transmitted helminths.

VARGAS P; JEUN R,; PILOTTE N; WILLIAMS S; GRANT J; KROLEWIECKI AJ; PAPAIAKOVOU M; CARO RN; CIMINO RO; MEJIA R

Atlanta

Congreso; 65th Annual Meeting of the American Society of Tropical Medicine and Hygiene; 2016

American Society of Tropical Medicine and Hygiene

Due to its simplicity and cost-effectiveness, microscopy has seen extensive field-use as the diagnostic standard for the detection of soil-transmitted helminths (STH) in stool samples. However, the sensitivity of microscopy-based detection is inadequate in reduced-transmission settings where worm burden is oftentimes low. Equally problematic, eggs of closely related species oftentimes have indistinguishable morphologies, leading to species misidentification. In light of these shortcomings, the purpose of this study was to demonstrate multi-parallel quantitative real-time PCR (qPCR) as the new ?gold standard? for STH detection. Accordingly, stool samples from non-endemic participants were spiked with limited numbers of eggs or larvae (1 to 40) of five different species of STH. DNA extracts were tested using two unique multi-parallel real-time PCR-based diagnostic methods. These methods employed different target sequences (ribosomal internal transcribed spacer, or highly repetitive non-coding regions), to evaluate the detection of DNA from as little as one egg per sample. There was a statistically significant spearman correlation between egg/larvae counts and qPCR from both methods for each one of the multi-parallel assays; for Ascaris lumbricoides (0.806), Ancylostoma duodenale (0.961), Necator americanus (1.00), Strongyloides stercoralis (0.835), and Trichuris trichiura (0.956) (p < 0.05 for all STH). Both methods had similar detection rates for 104 stool samples from a rural population in northern Argentina with less than a 25% variance between them for most STH. As parasitic targeting of two independent genomic regions provided reproducible results, we believe that, low cost multi-parallel quantitative real-time PCR-based diagnostics should supplant microscopy as the new gold standard for stool-based detection of soil transmitted helminths in public-health and community settings.