Evaluation of Urine CCA Assays for Detection of Schistosoma mansoni Infection in Western Kenya

Abstract

Although accurate assessment of the prevalence of Schistosoma mansoni is important for the design and evaluation of control programs, the most widely used tools for diagnosis are limited by suboptimal sensitivity, slow turn-around-time, or inability to distinguish current from former infections. Recently, two tests that detect circulating cathodic antigen (CCA) in urine of patients with schistosomiasis became commercially available. As part of a larger study on schistosomiasis prevalence in young children, we evaluated the performance and diagnostic accuracy of these tests—the carbon test strip designed for use in the laboratory and the cassette format test intended for field use. In comparison to 6 Kato-Katz exams, the carbon and cassette CCA tests had sensitivities of 88.4% and 94.2% and specificities of 70.9% and 59.4%, respectively. However, because of the known limitations of the Kato-Katz assay, we also utilized latent class analysis (LCA) incorporating the CCA, Kato-Katz, and schistosome-specific antibody results to determine their sensitivities and specificities. The laboratory-based CCA test had a sensitivity of 91.7% and a specificity of 89.4% by LCA while the cassette test had a sensitivity of 96.3% and a specificity of 74.7%. The intensity of the reaction in both urine CCA tests reflected stool egg burden and their performance was not affected by the presence of soil transmitted helminth infections. Our results suggest that urine-based assays for CCA may be valuable in screening for S. mansoni infections.

İran Doğu Azerbaycan Eyaletinde Çocuklarda Toksokariyazis Seroprevalansı

“…The present study reports serological prevalence of human toxocariasis in children of East Azerbaijan Province .In different parts of the world, serological studies have demonstrated a variation in Toxocara seroprevalence ranging from 2.3% to 86% 11,14 . However the present study showed a higher rate of infection (29.46 %) than that of (6.4 %) subjects residing in a rural area near Chandigarh 11 , Slovak Republic 15 which may be due to low standards of hygiene, frequent contact with the contaminated soil and less paternal education 23,26,27 . In our study, higher prevalence of infection was found among males than females.…”

Morbidity Associated with Schistosomiasis Before and After Treatment in Young Children in Rusinga Island, Western Kenya

“…Tests for antibodies to schistosomes were performed by enzyme-linked immunosorbent assay (ELISA) using soluble worm antigen preparation using previously described methods. 38 This test does not distinguish between Schistosoma spp.…”

Schistosomiasis among Young Children in Usoma, Kenya

“…20 A child with one or more positive stool slides or with positive SWAP ELISA results was considered infected with S. mansoni . Because Usoma has not been targeted by any preventive chemotherapy, positive serologic results were likely to represent true infections.…”

“…A fresh urine sample was also requested and was tested with a commercially available circulating cathodic antigen (CCA) assay (Rapid Medical Diagnostics, Pretoria, South Africa), which includes a standard curve that allows for a gross estimate of infection intensity. 20,21 Urine CCA was detected by carbon-conjugated antibody and measured as either negative or as 1-, 2-, or 3-plus. Among those children who tested positive for S. mansoni by stool and/or SWAP ELISA, infections were classified as low intensity (CCA negative or 1-plus), or high intensity (CCA 2-or 3-plus).…”