Comparison of Schistosoma mansoni Prevalence and Intensity of Infection, as Determined by the Circulating Cathodic Antigen Urine Assay or by the Kato-Katz Fecal Assay: A Systematic Review.

Nupur Kittur,Daniel G Colley,Carl H Campbell,Charles H King,Jennifer D Castleman

doi:10.4269/ajtmh.15-0725

Abstract

The relationship between results from Kato-Katz (KK) fecal microscopy and urine-based point-of-care circulating cathodic antigen (POC-CCA) assays for Schistosoma mansoni infection remains a critical issue. This systematic literature review of 25 published papers compares prevalence of S. mansoni infection by KK with that by the POC-CCA assay. Nineteen published studies met our inclusion criteria for data extraction and analysis. Above a prevalence of 50% by KK, KK and POC-CCA results yielded essentially the same prevalence. Below 50% prevalence by KK, the prevalence by the POC-CCA assay was between 1.5- and 6-fold higher and increased as prevalence by KK decreased. Five of nine publications met inclusion criteria for extractable data on intensity of S. mansoni infection by KK assay and visual band density using the POC-CCA assay. A clear positive relationship exists between intensity by the KK and POC-CCA assays. This systematic review indicates that below 50% prevalence, the POC-CCA assay is much more sensitive than the KK assay. However, the existing data are inadequate to precisely define the relationship between POC-CCA and KK at lower levels of KK prevalence. More studies directly comparing the two assays in low-prevalence areas are essential to inform decision-making by national schistosomiasis control programs.

Highlights

Planning for mass drug administration (MDA) to control Schistosoma mansoni requires accurate testing and mapping to determine local parasite prevalence
When KK prevalence was below 50%, the prevalence by point-of-care circulating cathodic antigen (POC-cathodic antigen (CCA)) was consistently higher
Our systematic review demonstrates that there is a real relationship between KK and POC-CCA prevalence, but it is nonlinear

Summary

INTRODUCTION

Planning for mass drug administration (MDA) to control Schistosoma mansoni requires accurate testing and mapping to determine local parasite prevalence. Because the KK assay is known to be less sensitive if prevalence and associated intensities of infection are low (or are being lowered due to multiple rounds of MDA),[3,4,5] the KK assay may no longer be a sufficiently sensitive mapping tool in many places, as the objectives of national programs move from morbidity control[6] toward interruption of transmission.[7,8]. A number of published studies indicate that the POC-CCA assay may be much more sensitive in detecting S. mansoni infection than the KK stool assay, especially in areas of low prevalence.[9,10,11,12,13,14,15,16] Latent class analysis of diagnostic characteristics in head-to-head trials has suggested that the POC-CCA assay has a considerably greater sensitivity and essentially comparable specificity as the KK assay.[13,14]. The second is to compare the intensity of infection among infected individuals, as determined by the KK assay (in eggs per gram [EPG] of feces), to the density of the band in the POC-CCA assay as determined by visual evaluation

MATERIALS AND METHODS

RESULTS

DISCUSSION