Identifying thresholds for classifying moderate-to-heavy soil-transmitted helminth intensity infections for FECPAKG2, McMaster, Mini-FLOTAC and qPCR.

• Published in: PLOS Neglected Tropical Diseases
• Main Authors: Bruno Levecke, Piet Cools, Marco Albonico, Shaali Ame, Cécile Angebault, Mio Ayana, Jerzy M Behnke, Jeffrey M Bethony, Giuseppe Cringoli, Daniel Dana, Bertrand Guillard, Nguyen Thi Viet Hoa, Gagandeep Kang, Deepthi Kattula, Jennifer Keiser, Andrew C Kotze, Leonardo F Matoso, Maria P Maurelli, James S McCarthy, Zeleke Mekonnen, Greg Mirams, Antonio Montresor, Rodrigo Corrêa Oliveira, Maria V Periago, Simone A Pinto, Laura Rinaldi, Somphou Sayasone, Laurentine Sumo, Louis-Albert Tchuem-Tchuenté, Dang Thi Cam Thach, Eurion Thomas, Ahmed Zeynudin, Jaco J Verweij, Johnny Vlaminck, Jozef Vercruysse
• Format: Article in Journal/Newspaper
• Language: English
• Published: Public Library of Science (PLoS) 2020
• Subjects: Arctic medicine. Tropical medicine; RC955-962; Public aspects of medicine; RA1-1270; Arctic
• Online Access: https://doi.org/10.1371/journal.pntd.0008296; https://doaj.org/article/5c1af073759a43d7aa4c8f37541899a3

The World Health Organization (WHO) has defined moderate-to-heavy intensity (M&HI) infections with soil-transmitted helminths (Ascaris lumbricoides, Trichuris trichiura and the two hookworms, Ancylostoma duodenale and Necator americanus) based on specific values of eggs per gram of stool, as measured by the Kato-Katz method. There are a variety of novel microscopy and DNA-based methods but it remains unclear whether applying current WHO thresholds on to these methods allows for a reliable classification of M&HI infections. We evaluated both WHO and method-specific thresholds for classifying the M&HI infections for novel microscopic (FECPAKG2, McMaster and Mini-FLOTAC) and DNA-based (qPCR) diagnostic methods. For this, we determined method-specific thresholds that best classified M&HI infections (defined by Kato-Katz and WHO thresholds; reference method) in two multi-country drug efficacy studies. Subsequently, we verified whether applying these method-specific thresholds improved the agreement in classifying M&HI infections compared to the reference method. When we applied the WHO thresholds, the new microscopic methods mainly misclassified M&HI as low intensity, and to a lesser extent low intensity infection as M&HI. For FECPAKG2, applying the method-specific thresholds significantly improved the agreement for Ascaris (moderate → substantial), Trichuris and hookworms (fair → moderate). For Mini-FLOTAC, a significantly improved agreement was observed for hookworms only (fair → moderate). For the other STHs, the agreement was almost perfect and remained unchanged. For McMaster, the method-specific thresholds revealed a fair to a substantial agreement but did not significantly improve the agreement. For qPCR, the method-specific thresholds based on genome equivalents per ml of DNA moderately agreed with the reference method for hookworm and Trichuris infections. For Ascaris, there was a substantial agreement. We defined method-specific thresholds that improved the classification of ...