Field-based evaluation of a reagent strip test for diagnosis of Schistosomiasis mansoni by detecting circulating cathodic antigen (CCA) in urine in low endemic area in Ethiopia

Abstract

Summary :The sensitivity, specificity, positive and negative predictive values of a reagent strip test for the diagnosis of schistosomiasis mansoni by detecting circulating cathodic antigen (CCA) in urine were evaluated using 184 stool and urine samples collected from schoolchildren living in relatively low endemic area of schistosomiasis mansoni in Ethiopia. A combined result of stool samples processed by Kato and formol-ether concentration methods was used as gold standard. The results showed that detection of CCA in urine using reagent strip test was slightly higher than the combined results of the stool techniques (65.2 % vs 42.4 %, p > 0.05) in suggesting the prevalence of the disease. The sensitivity, specificity, positive and negative predictive values of the reagent strip test were 76.9 %, 43.4 %, 50 % and 71.9 %, respectively. The result of egg counts using Kato method suggested that detection of urine CCA could be used to indicate the intensity of infection. Nevertheless, like that of stool examination, the reagent strip test was found to be less sensitive in case of light to moderate infections. About 23.1 % of the study children who were excreting the eggs of the parasite were found negative by the reagent strip test. The relative insensitivity of a reagent strip test in low intensity of infection necessitates for the development of more sensitive assay that can truly discriminate schistosome-infected from non-infected individuals. Résumé : ÉVALUATION SUR LE TERRAIN D'UN KIT DE DÉTECTION DANS LES URINES DES ANTIGÈNES CIRCULANTS CATHODIQUES POUR

Diagnosis of Schistosoma mansoni without the Stool: Comparison of Three Diagnostic Tests to Detect Schiostosoma mansoni Infection from Filtered Urine in Zambia

“…It has also been reported by several authors that even though it is easy to use, CCA shows reduced sensitivity in detecting urine CCA in low endemic areas of S. mansoni. 11,13,16,29 Moreover, urine CCA produces similar disease prevalence of multiple KK thick smears 10 and even multiple CCA testing does not improve the overall disease prevalence in comparison with a single CCA test, 15 this task is made more difficult to rationalize when, as shown here, neither CCA nor KK can detect all cases of parasitemia. The high level of specificity of infection in the current study is also related to the detection of S. mansoni-infected individuals, where KK and PCR perform exceptionally well (100%) and on the other hand CCA performs moderately (60%, Table 2).…”

“…Positivity of CCA is strongly correlated with S. mansoni infection intensities 10 and sensitivity of CCA decreases in low infection settings; light to moderate infections are frequently seen as negative by reagent strip test. 11,16 Moreover, CCA is also prone to produce false positive results 17 and inaccurately estimates disease prevalence 13 to light S. mansoni infections. As MDA initiatives expand in many countries, the subsequent decline in schistosome infection will require a more sensitive diagnostic test for S. mansoni.…”

“…[6][7][8][9] Moreover, this technique is limited caused by day-to-day fluctuation of egg output, 10 especially in a post-treatment situation. 11 As an alternative, a pointof-care CCA urine test has been developed for the diagnosis of…”

Magnetic Affinity Enzyme-Linked Immunoassay for Diagnosis of Schistosomiasis Japonicum in Persons with Low-Intensity Infection

“…[20][21][22] Use of the MEIA for antibody detection had been shown to be more sensitive than antigen detection and might be needed in areas characterized by low levels of transmission, low prevalence, and particularly low infection intensity. 13,23 In our study, we used SEA-MEIA for antibody detection to diagnose low-intensity infections of humans with S. japonicum.…”

Diagnosing schistosomiasis: where are we?

“…To date, currently available CCA tests have been shown to have moderate to good reliability in detecting S. mansoni 54,[61][62][63][64][65] but poor performance in detecting S. haematobium 61,[66][67][68][69] . Recently, the Bill & Melinda Gates Foundation sponsored evaluation studies on the accuracy of the urine CCA tests for determining schistosomiasis prevalence in young children in African countries.…”