The use of the circulating cathodic antigen (CCA) urine cassette assay for the diagnosis and assessment of cure of Schistosoma mansoni infections in an endemic area of the Amazon region

Abstract INTRODUCTION Schistosomiasis is a poverty-related disease that affects people in 78 countries worldwide. This study aimed to evaluate the point-of-care circulating cathodic antigen (POC-CCA) test performance using sensitive parasitological methods as a reference standard (RS) in individuals before and after treatment. METHODS The RS was established by combining the results of 16 Kato-Katz slides and the Helmintex® method. Positivity rates of the POC-CCA test and Kato-Katz and Helmintex® methods were calculated before treatment and 30 days afterward. Furthermore, the sensitivity, specificity, accuracy, and kappa coefficient before treatment were determined by comparing the methods. The cure rate was defined 30 days after treatment. RESULTS Among the 217 participants, the RS detected a total of 63 (29.0%) positive individuals. The POC-CCA test identified 79 (36.4%) infections. The evaluation of POC-CCA test performance in relation to the RS revealed a sensitivity of 61.9%, specificity of 74.0%, accuracy of 70.5%, and kappa coefficient of 0.33. Out of the 53 remaining participants after treatment, a total of 45 (81.1%) showed egg negative results, and 8 (18.9%) were egg positive according to the RS. A total of 5 (9.4%) egg-positive and 37 (69.8%) egg-negative individuals were positive by the POC-CCA test. CONCLUSIONS Our data show that the POC-CCA test has potential as an auxiliary tool for the diagnosis of Schistosoma mansoni infection, yielding better results than 16 Kato-Katz slides from three different stool samples. However, the immunochromatographic test lacks sufficient specificity and sensitivity for verifying the cure rate after treatment.

Schistosomiasis in the Amazon region: is the current diagnostic strategy still appropriate?

Abstract INTRODUCTION: This study analyzed the performance of the Kato Katz technique in detecting intestinal schistosomiasis in the State of Pará. METHODS: Of three stool samples provided by each of 380 participants, a total of 16 Kato Katz slides were examined to define the reference value (RV) of positives for comparisons. RESULTS: The RV revealed 37 (9.7%) infected participants in contrast to 10 (2.6%) according to a single slide. CONCLUSIONS: This significant underestimation of the infection rate gives reason to discuss if the current classification of prevalence levels reflects the real situation, principally in low transmission areas, like the Amazon region.