RESUMO
BACKGROUND: Rapid and early dengue diagnosis is essential for patient management and early disease intervention. MP Diagnostics ASSURE(®) Dengue IgA Rapid Test (Dengue IgA RT) was developed for the rapid detection of anti-dengue IgA in patients' biological samples. The performance of Dengue IgA RT was examined using multiple categories of well-characterized samples. MATERIALS AND METHODS: Dengue IgA RT was designed and developed. Following characterization of samples by reference ELISAs, the performance of the kit was evaluated. RESULTS: The overall sensitivity and specificity of Dengue IgA RT were 86.70% (n=233) and 86.05% (n=681) respectively; in which Dengue IgA RT detected 77.42% primary and 92.86% secondary cases; compared to 70.97% and 72.14% by IgM-Cap ELISA and 89.25% and 20% by Non-Structural Protein 1 (NS1) Ag ELISA respectively. Using 125 paired samples, Dengue IgA RT showed 84.80% sensitivity at acute phase and 99.20% sensitivity at convalescent phase; with 92% specificity at both phases. Dengue IgA RT also demonstrated a consistent performance (sensitivity: 85.53%, specificity: 80%) with 76 whole blood samples. In detecting all four serotypes of DENV (n=162), the performance of Dengue IgA RT was comparable with in-house IgM-Cap ELISA. Kinetics of anti-dengue IgA production was elucidated with 42.86% detection level as early as one-two days after fever onset, which increased to 83.33% between five and seven days after fever onset. CONCLUSION: Dengue IgA RT demonstrated a good performance and is applicable as one of the dengue early diagnostic tools at all levels of health care system.
RESUMO
ASSURE® Dengue IgA Rapid Test, an immunochromatographic anti-Dengue IgA Rapid Test based on reverse flow technology, was evaluated using archived sera. The sera were obtained during hospital admission and discharge of 204 patients during 2000 to 2001 dengue outbreak in Bangladesh and 220 negative sera collected in 2009. Based on characterization by reference ELISA (nonstructural protein 1 [NS1] Ag ELISA, immunoglobulin M [IgM]-Cap ELISA, and immunoglobulin G [IgG]-Cap ELISA), 179 (87.7%) patients were positive for dengue infection, and the remaining 245 patients had nondengue febrile illness. The performance of Dengue IgA Rapid Test was compared to reference ELISA. Of 179 dengue-positive sera, 79 (44.1%) were positive by NS1 Ag ELISA, 174 (97.2%) were positive by IgM-Cap ELISA, and 142 (79.3%) were positive by IgG-Cap ELISA. Among 142 IgG-positive cases, 121 (85.2%) patients had shown high level of IgG (PanBio units ≥ 22, equivalent to hemagglutination inhibition (HI) titer ≥ 2560) during hospital admission, indicating secondary infections. Dengue IgA Rapid Test demonstrated 99.4% (178 of 179) sensitivity in diagnosing dengue infection with the ability to detect 100% primary (58 of 58) and 99.2% (120 of 121) secondary infections, and the specificity was found 99.2% (2 of 245). The capability of Dengue IgA Rapid Test in detecting dengue infection in terms of day of illness was comparable to reverse transcriptase polymerase chain reaction and was found better than in-house IgM ELISA. Compared with in-house IgM ELISA, Dengue IgA Rapid Test also detected similar number of dengue virus (DENV) 1, DENV 2, and more DENV 3 and DENV 4 cases. The overall performance thus suggested its usefulness as one of the dengue early diagnostic tools where diagnostic facility is limited.