Diagnostic performance of a single and duplicate Kato-Katz, Mini-FLOTAC, FECPAKG2 and qPCR for the detection and quantification of soil-transmitted helminths in three endemic countries

Abstract

Background Because the success of deworming programs targeting soil-transmitted helminths (STHs) is evaluated through the periodically assessment of prevalence and infection intensities, the use of the correct diagnostic method is of utmost importance. The STH community has recently published for each phase of a deworming program the minimal criteria that a potential diagnostic method needs to meet, the so-called target product profiles (TPPs). Methodology We compared the diagnostic performance of a single Kato-Katz (reference method) with that of other microscopy-based methods (duplicate Kato-Katz, Mini-FLOTAC and FECPAK G2 ) and one DNA-based method (qPCR) for the detection and quantification of STH infections in three drug efficacy trials in Ethiopia, Lao PDR, and Tanzania. Furthermore, we evaluated a selection of minimal diagnostic criteria of the TPPs. Principal findings All diagnostic methods showed a clinical sensitivity of ≥90% for all STH infections of moderate-to-heavy intensities. For infections of very low intensity, only qPCR resulted in a sensitivity that was superior to a single Kato-Katz for all STHs. Compared to the reference method, both Mini-FLOTAC and FECPAK G2 resulted in significantly lower fecal egg counts for some STHs, leading to a substantial underestimation of the infection intensity. For qPCR, there was a positive significant correlation between the egg counts of a single Kato-Katz and the DNA concentration. Conclusions/Significance Our results indicate that the diagnostic performance of a single Kato-Katz is underestimated by the community and that diagnostic specific thresholds to classify intensity of infection are warranted for Mini-FLOTAC, FECPAK G2 and qPCR. When we strictly apply the TPPs, Kato-Katz is the only microscopy-based method that meets the minimal diagnostic criteria for application in the planning, monitoring and evaluation phase of an STH program. qPCR is the only method that could be considered in the phase that aims to seek confirmation for cessation of program. Trial registration ClinicalTrials.gov 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.…”

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].…”

“…Growing evidence suggests that these methods may be used to estimate infection intensity, although qPCR-based cutoffs for light, moderate, and heavy intensity infections have not yet been defined [24,27,28]. To our knowledge, six studies have compared diagnostic performance of copromicroscopic methods and qPCR; these studies reported that analyses classifying STH status using qPCR as a diagnostic tool showed higher prevalence compared to those using single and/or doubleslide Kato-Katz because of the higher sensitivity of the qPCR [18,23,25,[27][28][29].…”

Development of a Lab-on-a-Disk Platform with Digital Imaging for Identification and Counting of Parasite Eggs in Human and Animal Stool

“…It 2 of 15 is however a time-consuming technique, requiring expensive equipment. That is why there is a need to develop a tool, which is less expensive but as sensitive as qPCR [8].…”