BackgroundRapid tests detecting both dengue virus (DENV) NS1 antigen and anti-DENV IgM and IgG antibodies facilitate diagnosis of dengue fever (DF) in resource-poor settings. Methodology/principal findings92 acute phase serum samples from patients with a PCR-confirmed DENV infection collected in Lao People's Democratic Republic (Lao PDR) in 2013 and 2015 were analyzed with the SD Bioline Dengue Duo test. A subset of 74 samples was additionally tested with the Platelia NS1 antigen test, the Panbio DENV μ-capture ELISA and the Panbio DENV IgG ELISA. IgM seroconversion was assayed using follow-up samples of 35 patients collected in the convalescent phase. 57.6%, 22.8% and 44.6% of acute phase serum samples tested positive in the SD Bioline Dengue Duo NS1, IgM, and IgG test, respectively. Diagnostic sensitivity of the SD Bioline Dengue Duo NS1 test strongly correlated with viral load, decreased rapidly over the acute phase of the disease, and was significantly reduced in presence of high anti-DENV IgG antibody titers resulting from secondary DENV infection. While a good concordance (Cohen's kappa 0.78) was found between the SD Bioline Dengue Duo NS1 test and the Platelia NS1 antigen ELISA, both the SD Bioline Dengue Duo IgM and IgG test displayed a significantly lower sensitivity than the corresponding ELISA tests. The SD Bioline Dengue Duo test is a valuable tool for diagnosis of DENV infections especially when analyzing early acute phase samples with high viral load. Nevertheless, in endemic areas, where secondary flavivirus infections are common, diagnostic sensitivity of the NS1 and IgM test components may be compromised. PLOS ONE Performance evaluation of the SD Bioline Dengue Duo test PLOS ONE | https://doi.org/10.1371/journal.pone.0230337 March 17, 2020 2 / 17 PLOS ONE Performance evaluation of the SD Bioline Dengue Duo test PLOS ONE | https://doi.org/10.1371/journal.pone.0230337 March 17, 2020 3 / 17 m/f gender, n (%) 49/43 (53.3/46.7) days post onset, median (range) 4 (1-11) Ct pan-DENV PCR, median (range) 30.8 (19.3-40.9) DENV1/2/3/4 serotype, n (%) 2/28/50/12 (2.2/30.4/54.3/13.0)WBC in 10 3 μl -1 , median (range) 2.9 (1.0-12.0) WBC < reference, n (%) 66 (71.7) PLT in 10 3 μl -1 , median (range) 107.0 (2.0-411.0) PLT < reference, n (%) 67 (72.8) m: male, f: female, WBC: white blood cells, PLT: platelets, Ct: threshold cycle; reference values are 4.0-11.0 x 10 3 per μl for WBC and 150.0-450.0 x 10 3 per μl for PLT.

Objectives Dengue virus (DENV) detection by polymerase chain reaction (PCR) facilitates diagnosis of dengue fever, which is the most frequent arboviral disease globally. Two studies were performed in countries with high dengue incidence, to assess the diagnostic performance of different PCR techniques. Methods/Results Two hundred and seventy‐nine acute phase blood samples from febrile patients were analyzed for DENV by the RealStar Dengue RT‐PCR kit (Altona Diagnostics) as gold standard in comparison with the Tropical Fever Core multiplex PCR (Fast Track Diagnostics). In total, 102 samples collected in Savannakhet Province (Lao PDR, Southeast Asia) in 2013 and 35 samples from Valledupar (Colombia, South America) tested positive for DENV by RealStar RT‐PCR. In comparison, the Tropical Fever Core multiplex PCR detected 65.0% (65/102) and 68.6% (24/35) of these samples as positive for DENV in Savannakhet and Valledupar, respectively. Diagnostic sensitivity of the multiplex PCR strongly correlated with viral load. A subset of DENV PCR‐confirmed samples was additionally tested by BNITM in house Dengue Type RT‐PCR in comparison with two commercial test kits (RealStar Dengue Type RT‐PCR [Altona Diagnostics], Dengue differentiation PCR [Fast Track Diagnostics]). The leading dengue serotype in Savannakhet was DENV‐3 (58% [29/50]), while DENV‐1 (53.8% [14/26]) was the predominant serotype found in samples collected in Valledupar by BNITM‐type PCR. However, three DENV serotypes were circulating in Valledupar and in Savannakhet. In 2015, additional studies found predominantly DENV‐4 (71% [12/17]) in Savannakhet. Conclusions Both studies emphasized that routine diagnostics in both regions will benefit from an expanded use of highly sensitive pan‐dengue PCRs.