Prospective evaluation of the SD BIOLINE Dengue Duo rapid test during a dengue virus epidemic

Dengue virus is endemic in French Guiana with occurrence of cyclical outbreaks. There is a need for rapid tests allowing dengue laboratory diagnosis in healthcare centers scattered throughout this wide Amazonian territory. Our objective was to evaluate the real-life performance of the SD BIOLINE Dengue Duo (IgG/IgM + NS1 Ag) rapid test (RDT) during the 2012-2013 dengue epidemics. The RDT was evaluated in parallel with routine laboratory tests, PlateliaTM Dengue NS1 Ag and Focus Diagnostics Dengue Fever Virus IgM Capture DxSelect. A total of 3,347 patients with suspected dengue acute infection were evaluated. The diagnostic performances of the SD BIOLINE NS1 Ag were equivalent to Platelia NS1, 471 patients (14.1%) were NS1 Ag positive with the RDT and 14.2% with Platelia. The Cohen's Kappa coefficient was 0.86 [95%CI: 0.83-0.88], indicating an almost perfect agreement. Moreover, the sensitivity of SD BIOLINE NS1 Ag relative to the RT-PCR method was 87% [95%CI: 80-93%] and the specificity was 92% [95% CI: 87-97%]. However, the SD BIOLINE IgM test was found positive in 6.3% of the samples in comparison to 10.7% with Dx Select IgM. The Cohen's Kappa coefficient was 0.53 [95%CI: 0.47-0.58] indicating a moderate agreement. This raised concern about the SD BIOLINE IgM for the diagnostic of dengue in endemic areas. When considering only NS1 Ag results and not IgM, the RDT could be a viable solution to manage dengue outbreaks in healthcare centers where no laboratory services are available, in the early phase of the disease.