Performance of POC-CCA® in diagnosis of schistosomiasis mansoni in individuals with low parasite burden

Abstract

Introduction: Schistosomiasis, caused by Schistosoma mansoni, is a public health concern in Brazil. However, the most popular diagnostic method, the Kato-Katz technique, exhibits low sensitivity in low-endemicity areas. We aimed to compare the performance of an immunological assay, the point-of-care circulating cathodic antigen (POC-CCA®) test, with that of two parasitological techniques in a low-endemicity population. Methods: Our study included 141 individuals living in Estreito de Miralta, Minas Gerais, Brazil. Fecal samples were obtained from all participants and analyzed for schistosomiasis using two parasitological techniques: the Kato-Katz technique and the saline gradient technique. Additionally, POC-CCA® strips were utilized for testing urine samples. The results obtained by the different techniques were compared. Results: Analysis of two or 24 slides using the Kato-Katz technique resulted in a positivity rate of 10.6% (15/141) or 19.1% (27/141), respectively. The saline gradient technique yielded a positivity rate of 17.0% (24/141). The prevalence according to both parasitological techniques was 24.1% (34/141). The POC-CCA® test yielded a positivity rate of 22.7% (32/141); however, the positivity rate was merely 2.1% if trace results were considered negative. The agreements observed between POC-CCA® and the parasitological techniques were good (Kappa indexes > 0.64). The POC-CCA® test was more sensitive than the two-slide Kato-Katz technique (p < 0.05) in detecting cases of S. mansoni infection when trace results were considered positive. Conclusions: These findings reinforce the importance of using multiple diagnostic techniques in low-endemicity areas for effective control of disease.

Serological proteomic screening and evaluation of a recombinant egg antigen for the diagnosis of low-intensity infections in endemic area in Brazil Antigen target in schistosomiasis diagnosis

“…In this case, undiagnosed individuals would not receive treatment, possibly develop serious disease, and contribute to maintenance of transmission. On the other hand, rMEA-IgG-ELISA showed 87.5% (56/64) of sensitivity in the group of ≤ 10 epg, which is indicative of the majority of cases of schistosome infection in Brazil [10-12, 20, 27, 28]. Additional studies utilizing other S.mansoni recombinant proteins also showed better results than K-K performed by 2 slides in low-endemic areas.…”

“…In the majority of Brazilian endemic areas, transmission is maintained by individuals harboring low level infections that are undiagnosed by analysis of 2 slides of K-K in a single stool sample [6]. It has been suggested that a diagnostic test with high specificity and sensitivity will be needed for prevention, control and elimination of this disease [7, 12]. Some diagnostic methods have already shown their ability to detect positive individuals missed by parasitological techniques, due to low or absence of egg excretion [13, 14, 19].…”

“…However, the studies conducted in Brazil were controversial. The issues about adopting POC-CCA ® in Brazil are related to inadequate interpretation of trace as positive following the manufacturer’s recommendation and the low sensitivity to detect low-intensity infections [11, 12, 20, 27-33]. The authors emphasized differences regarding the predominance of extreme low-intensity infections (1-25 epg) found in the Brazilian areas [10-12].…”

“…The majority of studies validating POC-CCA were conducted in Africa, whereas few (10) studies were conducted in Brazil, which has a significantly different prevalence and morbidity profile. In contrast to Africa, most of the low-intensity infections in Brazil are denoted as < 25 epg [11, 12, 20, 27-33].…”

Detection of schistosomiasis in an area directly affected by the São Francisco River large-scale water transposition project in the Northeast of Brazil

“…The tests for the detection of circulating antigens have shown satisfactory results for the timely diagnosis, offering a promising complementary strategy to the traditional parasitological examination 42,43 . In this study, the positivity rate determined by the POC-CCA test was higher than that determined by the Kato-Katz technique, even with three slides.…”