Defining cutoffs for the Point-of-Care Circulating Cathodic Antigen (POC CCA) assay in areas of low Schistosoma mansoni prevalence in western Kenya

Safe Water And Aids Project (Swap), Kisumu

Investigators

Abstract

Project Abstract Monitoring and evaluation of control programs for Schistosoma mansoni is currently performed by detection of parasite eggs in stool samples using the Kato-Katz technique. This method has known limitations in sensitivity and requires trained microscopists and functional microscopes to perform the assessments. Recently (in 2008), a point of care (POC) test that detects S. mansoni circulating cathodic antigen (CCA) in urine has become commercially available. It is cheaper, easy to deploy, has greater sensitivity than stool exam and rapidly becomes negative upon successful treatment. At the WHO meeting on schistosome diagnostics in February 2015, the working group and subsequently the Strategic and Technical Advisory Group (STAG) encouraged additional validation of the POC-CCA to better define what cutoffs should be used for program decision making as well as for monitoring and evaluation for S. mansoni control programs. More data are needed on the performance of newly developed schistosomal antigen tests in endemic and post-MDA settings in order to be able to develop recommendations for programmatic use of these tools. Existing evidence suggests that in areas of high prevalence (? 50%), the Kato-Katz and POC-CCA assays both provide reasonable and comparable levels of prevalence and that the current guidelines are entirely adequate for morbidity control. However, there is a paucity of comparable data in areas of low (< 30%) prevalence. Thus, we propose in this study to evaluate the diagnostic performance of the POC CCA and Kato-Katz assays in areas of low S. mansoni prevalence in western Kenya. Findings from this study will help to clarify the relationship between Kato-Katz and POC-CCA and determine whether the visual POC- CCA band intensities can be used to evaluate treatment efficacy in order to inform program interventions.