Evaluation of point-of-contact circulating cathodic antigen assays for the detection of Schistosoma mansoni infection in low-, moderate-, and high-prevalence schools in western Kenya.

We evaluated the performance of a point-of-contact circulating cathodic antigen assay (POC-CCA) to detect schistosome infections in primary school children (N = 1,801) living in areas with low, moderate, and high Schistosoma mansoni prevalence in western Kenya. The commercially available assay (CCA-1) and a second, experimental formulation (CCA-2) were compared against Kato-Katz stool examinations and an anti-schistosome enzyme-linked immunosorbent assay (ELISA). A latent class model based on the four tests was used to establish "true infection status" in three different zones based on their distance from Lake Victoria. As a screening tool for community treatment according to World Health Organization (WHO) guidelines, the Kato-Katz examination was in closest agreement with the latent class model, followed by the experimental CCA-2, soluble adult worm antigen preparation (SWAP) ELISA, and CCA-1, which had high sensitivity compared with the other tests but was consistently the least specific. Our experience suggests that POC-CCA tests offer a field-friendly alternative to Kato-Katz, but need further interpretation for appropriate field use.

Cost analysis of tests for the detection of Schistosoma mansoni infection in children in western Kenya.

Financial resources tend to be limited in schistosomiasis endemic areas, forcing program managers to balance financial and scientific considerations when selecting detection assays. Therefore, we compared the costs of using single stool Kato-Katz, triplicate stool Kato-Katz, and point-of-contact circulating cathodic antigen (POC-CCA) assays for the detection of Schistosoma mansoni infection. Economic and financial costs were estimated from the viewpoint of a schistosomiasis control program using the ingredients approach. Costs related to specimen collection, sample processing and analysis, and treatment delivery were considered. Analysis inputs and assumptions were tested using one-way and two-way sensitivity analysis. The total per-person cost of performing the single Kato-Katz, triplicate Kato-Katz, and POC-CCA was US$6.89, US$17.54, and US$7.26, respectively. Major cost drivers included labor, transportation, and supplies. In addition, we provide a costing tool to guide program managers in evaluating detection costs in specific settings, as costs may vary temporally and spatially.