Abstract
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. 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. 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. These findings reinforce the importance of using multiple diagnostic techniques in low-endemicity areas for effective control of disease.
Highlights
Schistosomiasis, caused by Schistosoma mansoni, is a public health concern in Brazil
Circulating cathodic antigen (CCA) and circulating anodic antigen (CAA) are Schistosoma markers that can be detected in the serum and urine of infected individuals, and the levels of these antigens represent sensitive and specific biomarkers for the intensity of infection(8) (9)
In a study performed in an endemic area in the State of Minas Gerais, 100% of the individuals evaluated 30 days after schistosomiasis treatment resulted negative for serum CCA(10)
Summary
Schistosomiasis, caused by Schistosoma mansoni, is a public health concern in Brazil. 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. Convenience, and low cost, the Kato-Katz technique(3) is the most commonly used tool in the parasitological survey for the diagnosis of schistosomiasis and soil-transmitted helminths in stool samples from individuals living in endemic areas(4). In a study performed in an endemic area in the State of Minas Gerais, 100% of the individuals evaluated 30 days after schistosomiasis treatment resulted negative for serum CCA(10). This indicates that levels of serum and urine CCA and CAA decrease significantly some weeks after treatment, constituting a biomarker for schistosomiasis cure. Additional studies have found that detection of CCA and CAA offers some advantages for schistosomiasis diagnosis, such as the identification of active infections and a good diagnostic performance, in highly infected individuals(11) . (12)
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