Abstract
BackgroundChagas disease is a public health problem not only in Latin America, but also in other regions, including Spain, due to migration movements. Conventional serological diagnosis requires an invasive sample (plasma or serum) and a well-equipped laboratory. To circumvent those limitations, blood samples dried on filter paper (DBS) or Rapid Diagnostic Test (RDT) could be a practical alternative to reference protocol for serological screening in epidemiological studies. We evaluated the usefulness of dried blood sampling and a rapid diagnostic test (Trypanosoma Detect™) for the detection of antibodies against T. cruzi for their use in community-based screening.Methodology/Principal FindingsA total of 162 stored paired whole-blood and serum samples from Latin American migrants and 25 negative-control blood samples were included. Diagnosis of chronic Chagas disease was performed in serum according to WHO algorithms. Blood samples were retrospectively collected as dried spots and then analyzed using two different serological techniques, enzyme-linked immunosorbent assay (ELISA) and electrochemiluminescence immunoassay (E-CLIA). Whole-blood samples were also used to evaluate a rapid diagnostic test based on immunochromatography. A better correlation with conventional serum was observed in dried blood elutes using E-CLIA than ELISA (97% vs. 77% sensitivity, respectively). Both assays reported 100% specificity. The median cut-off index values of E-CLIA for dried blood were significantly lower than those for serum (138.1 vs. 243.3, P<0.05). The Trypanosoma Detect™ test presented a sensitivity and specificity of 89.6% and 100%, respectively.ConclusionsThe detection of antibodies against T. cruzi in dried blood samples shows a higher sensitivity when using E-CLIA compared with ELISA. Trypanosoma Detect™ is easier to use but has a lower sensitivity. Hence, we propose a sequential strategy based on performing the rapid test first, and a negative result will be confirmed by DBS-ECLIA for use in community Chagas disease screening programs.
Highlights
Chagas disease (CD), a neglected tropical disease caused by the parasite Trypanosoma cruzi, is estimated to affect between 6 and 8 million people worldwide (World Health Organization, 2020)
This study aims to evaluate the utility of dried blood spots (DBS) sampling and Rapid Diagnostic Test (RDT) in the detection of antibodies against T. cruzi for their application in community CD screening studies
T. cruzi infection status of the enrolled patients was established based on the consensus results of two conventional assays for IgG anti-T. cruzi (Pan American Health Organization, 2019): serum samples were tested by an electrochemiluminescence immunoassay (E-CLIA) (Elecsys Chagas, Roche Diagnostics, Manheim, Germany) and those with a positive result were subsequently analyzed using a commercial enzyme-linked immunosorbent assay (ELISA) (Ortho T. cruzi ELISA, Johnson & Johnson, High Wycombe, United Kingdom)
Summary
Chagas disease (CD), a neglected tropical disease caused by the parasite Trypanosoma cruzi, is estimated to affect between 6 and 8 million people worldwide (World Health Organization, 2020) This vector-borne disease, endemic in Latin America, has changed its epidemiology due to population migrations out of the endemic area (Stanaway and Roth, 2015). The vast majority of CD patients living in non-endemic areas are in the chronic stage of the disease (Pérez-Molina et al, 2012) The diagnosis of this phase relies on the detection of IgG antibodies against T. cruzi. Conventional serological diagnosis requires an invasive sample (plasma or serum) and a wellequipped laboratory To circumvent those limitations, blood samples dried on filter paper (DBS) or Rapid Diagnostic Test (RDT) could be a practical alternative to reference protocol for serological screening in epidemiological studies. We evaluated the usefulness of dried blood sampling and a rapid diagnostic test (Trypanosoma DetectTM) for the detection of antibodies against T. cruzi for their use in communitybased screening
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