Modification and optimization of the FECPAKG2 protocol for the detection and quantification of soil-transmitted helminth eggs in human stool

Abstract

BackgroundStandard diagnosis of human soil-transmitted helminth (STH) infections is based on the microscopic detection of helminth eggs in stool and supports programmatic decision making in control programs. However, the current standard diagnostic techniques still show a number of limitations. Recently, the FECPAKG2 method was developed to detect helminth infections and asses drug efficacy in sheep or cattle. It includes a device that takes digital images of helminth eggs that have been concentrated into one microscopic field of view and stores these images online for future evaluation. The goal of this study was to introduce a standard operating procedure (SOP) for the detection and quantification of human STH eggs using the FECPAKG2 and to optimize 2 crucial steps of the protocol, namely the sedimentation step (aimed at separating sinking eggs from floating debris) and the accumulation step (aimed at concentrating the eggs by flotation).Methodology/Principal findingsA total of 55 stool samples from naturally infected children were used from 4 different geographical areas (Ethiopia, Laos, Tanzania and Brazil). The results showed that Trichuris eggs generally moved slower than eggs of the other two STH species during both sedimentation in water in the FECPAKG2 sedimenter as during accumulation in flotation solution in the FECPAKG2 cassettes. The highest number of eggs were present in the slurry of the sedimenter after overnight sedimentation (Ascaris: 95.7%, Trichuris: 89.8% and hookworm: 94.2% of the eggs). A minimum of 24 minutes were needed to ensure the accumulation of at least 80% of the eggs from all three STH species in the FECPAKG2 cassette (Ascaris: 96.1%; Trichuris: 88.2% and hookworm: 87.6%).Conclusions/SignificanceThis study introduces for the first time a SOP for the FECPAKG2 method. Different aspects of the method for diagnosing human STH infections were optimized. Our study forms the basis for a thorough and objective evaluation of the system as a diagnostic tool that could be implemented in STH control programs.

Comparison of multi-parallel qPCR and double-slide Kato-Katz for detection of soil-transmitted helminth infection among children in rural Bangladesh

“…Diagnostic methods for STH include copromicroscopic methods, such as the Kato-Katz method [11,12], formol-ether concentration [13], FLOTAC [14], mini-FLOTAC [15][16][17][18], and FECPAK G2 [18,19]. Of these, Kato-Katz is the most commonly used diagnostic method for STH surveillance because it is inexpensive and relatively easy to perform in low-resource settings [20].…”

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

“…Ayana et al (in press) [ 36 ] describes the FECPAK G2 method for counting STH eggs in human stool. Stool analysis starts by weighing 3 grams of fresh stool in a Fill-FLOTAC.…”

“…More importantly, it opens the door to automated egg counting by egg recognition software [ 35 ]. Recently, Ayana et al (in press) [ 36 ] modified and optimized a FECPAK G2 protocol for the detection and quantification of human STH eggs in stool. However, it remains unclear whether it provides equivalent ERR results to those obtained by diagnostic methods recommended by WHO, and whether it would result in more efficient use of financial and technical resources under field conditions.…”

The contribution of the veterinary helminthology to medical helminthology

“…FECPAKG2 generates results quickly and easily. Recently, Ayana et al (2018) modified and optimized a FECPAKG2 protocol for the detection and quantification of human STH eggs in stool samples. With the development of the SERASCA®-test, a new and improved method is now available for the diagnosis of Ascaris suum infection pressure in fattening pigs (Vlaminck et al 2012).…”

“…ABZ showed a higher efficacy against hookworms (> 95%) compared to MEB (80%). The findings also emphasized the need to revise the WHO recommended efficacy threshold for single dose of MEB and ALB treatments and to determine efficacy levels below which should raise concern about the possible emergence of drug resistance (Vercruysse et al 2011;Vlaminck et al 2018).…”