Field assessment in Cameroon of a reader of POC-CCA lateral flow strips for the quantification of Schistosoma mansoni circulating cathodic antigen in urine.

Estelle Mezajou Mewamba,Arnol Auvaker Zebaze Tiofack,Harry Noyes,Romuald Isaka Kamwa Ngassam,Gustave Simo,Cyrille Nguemnang Kamdem,Hilaire Marcaire Womeni,Flobert Njiokou,Oscar Nyangiri,Mureille Carole Tchami Mbagnia,Jessica K Fairley

doi:10.1371/journal.pntd.0009569

Estelle Mezajou Mewamba, Arnol Auvaker Zebaze Tiofack + Show 9 more

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https://doi.org/10.1371/journal.pntd.0009569

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Journal: PLoS neglected tropical diseases	Publication Date: Jul 14, 2021
Citations: 17	License type: CC BY 4.0

Abstract

Determining Schistosoma mansoni infection rate and intensity is challenging due to the low sensitivity of the Kato-Katz (KK) test that underestimates the true disease prevalence. Circulating cathodic antigen (CCA) excreted in urine is constantly produced by adult worms and has been used as the basis of a simple, non-invasive point of care test (POC-CCA) for Schistosoma mansoni infections. Although the abundance of CCA in urine is proportional to worm burden, the POC-CCA test is marketed as a qualitative test, making it difficult to investigate the wide range of infection intensities. This study was designed to compare the prevalence and intensity of S. mansoni by KK and POC-CCA and quantify, on fresh and frozen (<-20°C) urine samples, CCA using the visual scores and the ESEquant LR3 reader. Stool and urine samples were collected from 759 school-aged children. The prevalence and intensity of S. mansoni were determined using KK and POC-CCA. The degree of the positivity of POC-CCA was estimated by quantifying CCA on fresh and frozen urine samples using visual scores and strip reader. The prevalence, the infection intensity as well the relative amounts of CCA were compared. The S. mansoni infection rates inferred from POC-CCA and KK were 40.7% and 9.4% respectively. Good correlations were observed between infection intensities recorded by; i) the reader and visual scoring system on fresh (Rho = 0.89) and frozen samples (Rho = 0.97), ii) the reader on fresh urine samples and KK (epg) (Rho = 0.44). Nevertheless, 238 POC-CCA positive children were negative for KK, and sixteen of them had high levels of CCA. The correlation between results from the reader on fresh and frozen samples was good (Rho = 0.85). On frozen samples, CCA was not detected in 55 samples that were positive in fresh urine samples. This study confirmed the low sensitivity of KK and the high capacity of POC-CCA to provide reliable data on the prevalence and intensity of S. mansoni infections. The lateral flow reader enabled accurate quantification of CCA under field conditions on fresh and frozen urine samples with less time and effort than KK.

Highlights

Schistosomiasis is one of the most common neglected tropical diseases (NTD) and remains a major public health problem in many tropical and subtropical countries [1]
This study confirmed the low sensitivity of KK and the high capacity of POC-cathodic antigen (CCA) to provide reliable data on the prevalence and intensity of S. mansoni infections
Several strategies including preventive chemotherapy (PCT), water sanitation and hygiene (WASH), snail control, and the dissemination of information, education, and communication (IEC) have been developed to fight against schistosomiasis [7], the control of this disease relies mainly on PCT in which Praziquantel (PZQ) is distributed to school-aged children (SAC) once a year, twice a year or every 2 years depending on the current disease prevalence in the endemic area [8,9]

Summary

Introduction

Schistosomiasis is one of the most common neglected tropical diseases (NTD) and remains a major public health problem in many tropical and subtropical countries [1]. Several strategies including preventive chemotherapy (PCT), water sanitation and hygiene (WASH), snail control, and the dissemination of information, education, and communication (IEC) have been developed to fight against schistosomiasis [7], the control of this disease relies mainly on PCT in which Praziquantel (PZQ) is distributed to school-aged children (SAC) once a year, twice a year or every 2 years depending on the current disease prevalence in the endemic area [8,9]. Determining the accurate disease prevalence and the infection intensity in different communities with reliable tools appears as the keystone for monitoring progress towards control of schistosomiasis in endemic areas. Circulating cathodic antigen (CCA) excreted in urine is constantly produced by adult worms and has been used as the basis of a simple, non-invasive point of care test (POC-CCA) for Schistosoma mansoni infections. This study was designed to compare the prevalence and intensity of S. mansoni by KK and POC-CCA and quantify, on fresh and frozen (

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Conclusion