Evaluation, Validation, and Recognition of the Point-of-Care Circulating Cathodic Antigen, Urine-Based Assay for Mapping Schistosoma mansoni Infections

Abstract

Efforts to control Schistosoma mansoni infection depend on the ability of programs to effectively detect and quantify infection levels and adjust programmatic approaches based on these levels and program goals. One of the three major objectives of the Schistosomiasis Consortium for Operational Research and Evaluation (SCORE) has been to develop and/or evaluate tools that would assist Neglected Tropical Disease program managers in accomplishing this fundamental task. The advent of a widely available point-of-care (POC) assay to detect schistosome circulating cathodic antigen (CCA) in urine with a rapid diagnostic test (the POC-CCA) in 2008 led SCORE and others to conduct multiple evaluations of this assay, comparing it with the Kato-Katz (KK) stool microscopy assay-the standard used for more than 45 years. This article describes multiple SCORE-funded studies comparing the POC-CCA and KK assays, the pros and cons of these assays, the use of the POC-CCA assay for mapping of S. mansoni infections in areas across the spectrum of prevalence levels, and the validation and recognition that the POC-CCA, although not infallible, is a highly useful tool to detect low-intensity infections in low-to-moderate prevalence areas. Such an assay is critical, as control programs succeed in driving down prevalence and intensity and seek to either maintain control or move to elimination of transmission of S. mansoni.

Circulating Anodic Antigen (CAA): A Highly Sensitive Diagnostic Biomarker to Detect Active Schistosoma Infections—Improvement and Use during SCORE

“…3,4 This antigen is distinct from the circulating cathodic antigen (CCA) used in the point-of-care (POC) CCA mapping tool for S. mansoni. 2 CAA's polysaccharide structure renders it very stable, and it has not been identified in organisms other than schistosomes. CAA has a strong negative charge and is at least 10 kDa, but can vary in molecular weight.…”

“…SCORE's work on such tools for the mapping of schistosomiasis is described in another article in this supplement. 2 In addition to better mapping diagnostic assays, developing a highly sensitive and specific test for detection of infection with Schistosoma mansoni and Schistosoma haematobium has also been a high priority. Such an assay is likely to increase in importance as prevalence and intensity continue to decrease in many places and elimination is within reach.…”

“…In 2009, SCORE held a meeting to help define which of the many opportunities for investment in diagnostics would be most likely to yield concrete results that would be of use to control and elimination programs within the SCORE time frame. 2 Participants included individuals working with parasite diagnostics and those using cutting-edge technologies for other detection purposes. Discussions covered a range of approaches-including nucleic acid, antigen, and antibody tests.…”

Schistosomiasis: an epidemiological update on Brazil's southernmost low endemic area in Esteio

“…Antigen detection in urine is a promising alternative as a screening tool for the Kato-Katz method in areas with high endemicity 20,21 . In contrast, the performance of POC-CCA may be unreliable in low endemicity areas [22][23][24][25] .…”

SCORE Operational Research on Moving toward Interruption of Schistosomiasis Transmission

“…SCORE's work on developing and evaluating mapping and diagnostic tools is described in other articles in this supplement. 2,3 In 2012, the World Health Assembly (WHA) issued resolution WHA 65.21, which called for the expansion of schistosomiasis control programs and to "initiate elimination campaigns where appropriate." 4 Following this, in 2013, SCORE received supplemental funding from the BMGF to build on data and experiences obtained by SCORE thus far and expand operational research on elimination of schistosomiasis.…”