Validity of urine-CCA cassette test and indirect haem-agglutination assay (IHA) in the detection of schistosomiasis-mansoni infection relative to microscopic examination.

Abstract

Several immunodiagnostic assays have been commercially presented over the last years as easy diagnostic methods for schistosomiasis using serum or urine samples. The performance of immunochromatographic test (ICT) and indirect hemagglutination assay (IHA) was validated in the identification of active schistosomiasis infection. Detection of circulating cathodic antigen (CCA) of the parasite in urine samples and anti-Schistosoma antibodies in serum using ICT (Urine-CCA Cassette test) and IHA respectively. Proved diagnosis of Schistosoma mansoni infection was defined by the sum of positive results from microscopic examination (Gold standard) and Kato-Katz method. Out of 173 (mean age, 45 ± 10years; 70 from Giza, 103 from different Egyptian governorates), 9 4 adult patients were infected. Urine-CCA cassette test despite showing high specificity (91.14%) it was of low sensitivity (23.40%). PPVs was 75.86% and NPV was 50.00% and diagnostic accuracy of 54.34%. The IHA showed a sensitivity of 57.45% and specificity of 48.10%. PPVs was 56.84% whereas NPVs was 48.72%. As for diagnostic accuracy, it was 53.18%. Urine-CCA Cassette test had lower sensitivity than expected for detection of circulating antigen and the IHA kit is generally more expensive than microscopic examination and Urine-CCA cassette test with low sensitivity and specificity. On the basis of this diagnostic performance none of the two tested immune-assays can be a sole tool in the principal diagnosis of active schistosomiasis infections.