Resumo

Dengue is an important cause of acute febrile disease which presents as asymptomatic to severe infection. Since clinical manifestations are non-specific, laboratory investigation is an important point in DENV infection diagnosis. However, immunological and molecular diagnostic tests (DT) accuracy may vary and compromise confirmation of early acute DENV infection. Herein, we examined the performance of DT in a population with a broad clinical presentation attending a tertiary hospital. The study aims to evaluate DT accuracy in early acute DENV infection diagnosis. Total blood was collected for RNA detection by in house RT- PCR. A set of universal primers (D1 and D2) were used followed by semi-nested PCR assay for DENV serotyping. 24 total blood samples were obtained from clinical suspected individuals of having Dengue during the outbreak of April-May / 2013. Moreover, we used a serum panel of 72 samples to evaluate the accuracy of commercially available anti-DENV IgM and IgG detection assays: immunochromatic test (Bioeasy Diagnóstica S/A, Brazil) and ELISA (PanBio, Australia). RT-PCR confirmed acute infection in 4 out of 24 (16.67%) of tested samples all belonging to DENV4 serotyping. In addition, DENV 4 RNA was amplified until day 9 post infection. On the other hand, NS1 antigen was only detectable in 1 out of 24 (4.17%) tested samples. Accuracy of the immunodiagnostic tests was also determined. IgM reactivity was detected by immunochromatic test and ELISA in 13 (18.1%) and 25 (34.7%) out of 72 tested samples, respectively. Furthermore, immunochromatic test for IgG detection showed reactivity in 10 (13.9%) out of 72 tested samples in contrast to 64 (86.1%) detected by ELISA-IgG. The concordance between the immunochromatic test and ELISA for IgM detection was 18 (25%) out of 72 tested samples while the agreement between immunochromatic test and ELISA for IgG detection was 42 (58.3%) out of 72 samples. Our results demonstrated that immunochromatic test was inferior when compared to ELISA-IgM and IgG to detect both acute primary, secondary and DENV past infection as well. Commercially available rapid test analyzed in this study for detection of IgM / IgG showed low reactivity and loss of sensitivity, which may compromise the diagnosis of DENV infection.