UP-Converting Phosphor - Lateral Flow, KATO-KATZ E POC-CCA: uma análise comparativa no diagnóstico da infecção por Schistosima mansoniI em uma área de baixa edemicidade

Abstract

Schistosomiasis affects at least 230 million people and is associated with at least 200,000 deaths a year worldwide. The detection of Schistosoma circulating antigens is becoming a promising tool for the diagnosis of active infection. Serum levels of these antigens are related to the parasite load and the intensity of infection and decrease rapidly after drug treatment, demonstrating also be a useful approach of therapeutic response evaluation. It was evaluated the prevalence of active S. mansoni infection by testing Up-Converting Phosphor Lateral Flow (UCP-LF) for determination of Circulating Anodic Antigen (CAA) in urine and it was compared with the Kato-Katz's technique for detection of eggs in the feces and with the Point-of-Care–CCA (POC-CCA) test, which detects the Circulating Cathodic Antigen (CCA) in the urine. Moreover, the therapeutic response was evaluated by the methods that detect circulating antigens six weeks after treatment. The study was conducted in Bananeira ́s, village - Capistrano town, an endemic area in the Ceara state. From 297 in habitants of the village, 285 agreed to participate in the study, of whom 159 received treatment. Of these, 128 returned the required urine and feces before and after treatment and were evaluated by three methods. The UCP-LF CAA test detected 44 positive (34.4%). The Kato-Katz technique revealed only two positive feces samples (1.6%) and POC-CCA detected 8 positive (6.2%). The sensitivity of the different assays were determined against a combined infection positive ("gold") standard, being higher for the test CAA UCP-LF (92%), followed by POC-CCA (17%), while the Kato-Katz (three slides) had a very low sensitivity (4%).The highest prevalence rate was found active infections in people aged 30-39 years.CAA concentrations before treatment ranged from 0.16 to 61.12 pg CAA / ml of urine, with a significant decrease in the levels of CAA after six weeks of treatment (Wilcoxon, p = 0.003). Thus, given these promising observations, the UCP-LF CAA showed a potential value to determine the prevalence of schistosomiasis in low endemic areas; however, other larger studies are needed.