Intestinal schistosomiasis: Can a urine a sample decide the infection? –

01 Oct 2020

Intestinal schistosomiasis, one of the neglected tropical diseases whose control depends on accurate diagnosis of the disease prevalence. The use of low sensitive Kato Katz (KK) fecal egg detection method as a reference gold standard is not an accurate indication especially in low transmission areas. Latent class analysis frameworks especially the Bayesian could be used instead to compare between different diagnostic tests without the use of a gold standard method as a reference. Thus, this study compared two urine-based tests for the detection of circulating antigen and cell free DNA of Schistosoma mansoni versus KK method using the Bayesian latent class analytical framework and in two models where the trace results of point of contact - assay of circulating cathodic antigen (POC-CCA) were once estimated as positive, and as negative in the other model. The Bayesian framework in the trace CCA positive model showed an estimate of disease prevalence of 26% (95% BCI:0 to 60%). POC-CCA showed the highest sensitivity (74% with BCI: 9 to 91%) and lowest specificity for (20% with BCI: 0% to 37%) and the reverse for KK. For POC-CCA with traces considered negative, it was found that results between the three tests were moderated where the positivity for infection by Schistosoma antigen detection and PCR for cell free DNA approached that estimated by the Bayesian framework (44%), and the specificity for point of contact assay(81%; 95%BCI: 59% to 100%) rose in hand with its sensitivity(77%, 95% BCI:53% to 100%) and with results for PCR test (sensitivity = 80%; 95% BCI: 61% to 100%, specificity = 69%; 95% BIC: 47% to 100%). KK remains with the highest specificity while its sensitivity in the two models never exceeded 22%. Thus, we conclude that the use of a single urine sample could be very sensitive and highly specific in the diagnosis of intestinal schistosomiasis using either the trace negative model of point of contact assay, or conventional PCR, when compared to the fecal egg detection using duplicate KK. However, the use of a single tool restricts the management of the disease in areas of low endemicity.