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Objectives. To assess the diagnostic performance of the SD dengue DUO rapid test (Inyecta) for the detection of NS1, IgM and IgG in comparison to the ELISA test. Materials and methods. This is a diagnostic test evaluation that included 286 serum samples from patients with symptomatology attributable to dengue from endemic areas of Peru. The samples were analyzed by ELISA and the SD dengue DUO rapid test (Inyecta) for IgM, NS1 and IgG at the Instituto de Investigación Nutricional in Lima. Results. The sensitivity of the rapid test was 68.0% for NS1 and IgM, and 86.0% for IgG, improving to 75.0% and 81.0% for NS1 and IgM, respectively, during the first three days. The specificity for all three analytes was greater than 87.0%. The concordance of the results, measured by the Kappa coefficient for the three analytes, was good and no cross-reaction with other arboviruses was found. Conclusions. The SD dengue DUO rapid test allows detection of NS1, IgM and IgG with adequate sensitivity and specificity. Sensitivity for IgM and NS1 increases when detected during the first three days of symptoms. Therefore, we recommend its implementation in primary care centers for early and timely diagnosis. [ABSTRACT FROM AUTHOR]

BACKGROUND: Dengue fever (DF) is an acute febrile arboviral disease affecting the tropical and subtropical regions of the world. It is known that early and specific diagnosis of dengue hemorrhagic fever (DHF) or dengue shock syndrome (DSS), followed by supportive therapy, reduces morbidity and mortality. Serum levels of secreted NS1 positively correlate with viral titers and have been a useful tool in dengue infection (DI) diagnosis. NS1 detection is reported to be sensitive as well as highly specific. Apart from the dengue-specific parameters, platelet count is the only accessory laboratory test available in the peripheral areas that can support the diagnosis of DHF or DSS. In this study, we tried to correlate the platelet counts and immunochromatography (ICT)-based dengue serology tests. METHODS: A total of 525 serum samples from clinically suspected DF were collected. The samples were tested immediately for NS1, immunoglobulin M (IgM), and IgG by ICT-based tests. Platelet counts of all the cases positive for any of the dengue parameters were noted. The statistical analysis was performed using Z-test. RESULTS: One hundred and nine specimens were tested positive for either one or more of the three markers (NS1, IgM, and IgG). Platelet count <1,00,000/ml was noticed in 65 cases (%) of 109 dengue-positive cases. Of 79 cases who were positive for NS1 antigen only, thrombocytopenia was observed in 44 cases, whereas thrombocytopenia was observed in six of six cases positive for NS1 + IgM. The association of thrombocytopenia in NS1 + IgM-positive cases was statistically significant (Z = 2.125, P = 0.0331). CONCLUSION: In the present study, association of thrombocytopenia in dengue parameter-positive cases was found to be highly significant. ICT is the only excellent tool as it is easy, rapid, and easily available in areas with poor resources. Apart from dengue-specific parameters, platelet count is the only accessory laboratory test available in the peripheral areas that can support the diagnosis of DI. [ABSTRACT FROM AUTHOR]

A dengue outbreak abruptly occurred at the border of China, Myanmar, and Laos in June 2017. By November 3rd 2017, 1184 infected individuals were confirmed as NS1-positivein Xishuangbanna, a city located at the border. To verify the causative agent, complete genome information was obtained through PCR and sequencing based on the viral RNAs extracted from patient samples. Phylogenetic trees were constructed by the maximum likelihood method (MEGA 6.0). Nucleotide and amino acid substitutions were analyzed by BioEdit, followed by RNA secondary structure prediction of untranslated regions (UTRs) and protein secondary structure prediction in coding sequences (CDSs). Strains YN2, YN17741, and YN176272 were isolated from local residents. Stains MY21 and MY22 were isolated from Burmese travelers. The complete genome sequences of the five isolates were 10,735 nucleotides in length. Phylogenetic analysis classified all five isolates as genotype I of DENV-1, while isolates of local residents and Burmese travelers belonged to different branches. The three locally isolates were most similar to the Dongguan strain in 2011, and the other two isolates from Burmese travelers were most similar to the Laos strain in 2008. Twenty-four amino acid substitutions were important in eight evolutionary tree branches. Comparison with DENV-1SS revealed 658 base substitutions in the local isolates, except for two mutations exclusive to YN17741, resulting in 87 synonymous mutations. Compared with the local isolates, 52 amino acid mutations occurred in the CDS of two isolates from Burmese travelers. Comparing MY21 with MY22, 17 amino acid mutations were observed, all these mutations occurred in the CDS of non-structured proteins (two in NS1, 10 in NS2, two in NS3, three in NS5). Secondary structure prediction revealed 46 changes in the potential nucleotide and protein binding sites of the CDSs in local isolates. RNA secondary structure prediction also showed base changes in the 3′UTR of local isolates, leading to two significant changes in the RNA secondary structure. To our knowledge, this study is the first complete genome analysis of isolates from the 2017 dengue outbreak that occurred at the border areas of China, Burma, and Laos. [ABSTRACT FROM AUTHOR]

INTRODUCTION: Early diagnosis of dengue is important for appropriate clinical management and vector control. Different serological tests based on the principle of immunochromatography and enzyme‑linked immunosorbent assay (ELISA) are commonly used for detection of antigen and antibodies of dengue virus. The performance of these tests depends on the sensitivity and specificity. Hence, the study was undertaken to compare nonstructural protein‑1 (NS1) antigen detection by rapid and ELISA with real‑time polymerase chain reaction (RT‑PCR) for diagnosis of dengue. MATERIALS AND METHODS: Prospective laboratory study was carried out on sera samples (n = 200) from clinically suspected cases of dengue. The sera samples were subjected for NS1 antigen detection test by rapid test, NS1 ELISA, and RT‑PCR. The results of rapid and ELISA tests were compared with real Time PCR. RESULTS: The sensitivity, specificity, positive, and negative predictive value of rapid dengue NS1 antigen test were 81.5%, 66.7%, 78.2%, and 71.1%, respectively whereas that of NS1 ELISA were 89.9%, 100%, 100%, and 94%, respectively. Concordance of Rapid NS1 and NS1 ELISA with PCR was 75.5% and 94%. DISCUSSION AND CONCLUSION: NS1 antigen ELISA can be implemented in diagnostic laboratories for diagnosis of dengue in the acute phase of illness. The test also has great potential value for use in epidemic situations, as it could facilitate the early screening of patients and limit disease expansion. [ABSTRACT FROM AUTHOR]

Background: The co-circulation of 4 DENV serotypes in geographically expanding area, has resulted in increasing occurrence of DENV co-infections. However, studies assessing the clinical impact of DENV co-infections have been scarce and have involved small number of patients. This study explores the impact of DENV co-infection on clinical manifestations and laboratory parameters.Methods: This retrospective study involved consecutive hospitalized patients with non-structural protein 1 (NS1) antigen positivity during an outbreak (Jan to April 2014). Multiplex RT-PCR was performed directly on NS1 positive serum samples to detect and determine the DENV serotypes. All PCR-positive serum samples were inoculated onto C6/36 cells. Multiplex PCR was repeated on the supernatant of the first blind passage of the serum-infected cells. Random samples of supernatant from the first passage of C6/36 infected cells were subjected to whole genome sequencing. Clinical and laboratory variables were compared between patients with and without DENV co-infections.Results: Of the 290 NS1 positive serum samples, 280 were PCR positive for DENV. Medical notes of 262 patients were available for analysis. All 4 DENV serotypes were identified. Of the 262 patients, forty patients (15.3 %) had DENV co-infections: DENV-1/DENV-2(85 %), DENV-1/DENV-3 (12.5 %) and DENV-2/DENV-3 (2.5 %). Another 222 patients (84.7 %) were infected with single DENV serotype (mono-infection), with DENV- 1 (76.6 %) and DENV- 2 (19.8 %) predominating. Secondary dengue infections occurred in 31.3 % patients. Whole genome sequences of random samples representing DENV-1 and DENV-2 showed heterogeneity amongst the DENVs. Multivariate analysis revealed that pleural effusion and the presence of warning signs were significantly higher in the co-infected group, both in the overall and subgroup analysis. Diarrhoea was negatively associated with co-infection. Additionally, DENV-2 co-infected patients had higher frequency of patients with severe thrombocytopenia (platelet count < 50,000/mm(3)), whereas DENV-2 mono-infections presented more commonly with myalgia. Elevated creatinine levels were more frequent amongst the co-infected patients in univariate analysis. Haemoconcentration and haemorrhagic manifestations were not higher amongst the co-infected patients. Serotypes associated with severe dengue were: DENV-1 (n = 9), DENV-2 (n = 1), DENV-3 (n = 1) in mono-infected patients and DENV-1/DENV-2 (n = 5) and DENV-1/DENV-3 (n = 1) amongst the co-infected patients.Conclusion: DENV co-infections are not uncommon in a hyperendemic region and co-infected patients are skewed towards more severe clinical manifestations compared to mono-infected patients. [ABSTRACT FROM AUTHOR]

Dengue virus (DENV) nonstructural-1 (NS1) glycoprotein is useful for diagnosis of DENV infections in the first 8 days of illness with any of the four serotypes (DENV-1, DENV-2, DENV-3 and DENV-4). However, NS1 diagnostics are less sensitive for secondary DENV infections so the utility of NS1 diagnostics in dengue endemic countries where there is predominantly secondary infections is being questioned. Heat-mediated immunecomplex dissociation (ICD) prior to testing serum samples can significantly improve NS1 test sensitivity in secondary infections but requires monoclonal antibodies (MAbs) reactive to heat-denatured NS1. In order to incorporate a simple heat-mediated ICD step, a crucial step was to develop new MAbs with high affinity and specificity to heat-denatured DENV NS1 protein. In the present study, six new MAbs were isolated from BALB/c mice immunized with recombinant monomeric NS1 of DENV-1 and DENV-2. Characterization using three different methods: indirect ELISA, fixed cell ELISA and western blot revealed that all six MAbs are serotype-cross-reactive and capable of recognizing dimeric and hexameric isoforms as well as heat-denatured NS1 from all four DENV serotypes. No cross-reactivity to NS1 of West Nile virus and Yellow fever virus was observed on western blot and indirect ELISA. Five of the six MAbs mapped to the DENV NS1 region of 105–119 amino acids. The remaining MAb mapped to DENV NS1 region of 25–39 amino acids. These two NS1 regions were found to be highly conserved among all four DENV serotypes by sequences analysis and database comparison. These MAbs were used to develop an NS1 capture ELISA and tested using a small panel of clinical specimens. The results from the NS1 capture ELISA indicated at least a three-fold increase in NS1 antigen detection in heat-denatured samples compared to untreated specimens. Furthermore, artificial immunecomplexed results also demonstrated the binding efficiency of these MAbs to heat denatured NS1. Taken together, these MAbs allow for the incorporation of a heat dissociation step to improve the sensitivity of DENV NS1 antigen detection in secondary infections. [ABSTRACT FROM AUTHOR]

Early diagnosis of dengue virus (DENV) is important. There are numerous products on the market claiming to detect DENV NS1, but these are not always reliable. In this study, a highly sensitive and accurate rapid diagnostic test (RDT) was developed using anti-dengue NS1 monoclonal antibodies. A recombinant NS1 protein was produced with high antigenicity and purity. Monoclonal antibodies were raised against this purified NS1 antigen. The RDT was constructed using a capturing (4A6A10, K d = 7.512 ± 0.419 × 10 −9 ) and a conjugating antibody (3E12E6, K d = 7.032 ± 0.322 × 10 −9 ). The diagnostic performance was evaluated with NS1-positive clinical samples collected from various dengue endemic countries and compared to SD BioLine Dengue NS1 Ag kit. The constructed RDT exhibited higher sensitivity (92.9%) with more obvious diagnostic performance than the commercial kit (83.3%). The specificity of constructed RDT was 100%. The constructed RDT could offer a reliable point-of-care testing tool for the early detection of dengue infections in remote areas and contribute to the control of dengue-related diseases. [ABSTRACT FROM AUTHOR]

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An error occurred during the publication of the original article [1]. [ABSTRACT FROM AUTHOR]

Background Early detection of complications significantly reduces dengue associated mortality and morbidity. We set out to determine if the NS1 rapid antigen detection test could be used as a point of care test to predict severe disease. Methods 186 adult patients with confirmed dengue were enrolled during day 3-8 of illness. Clinical and laboratory parameters were recorded during the course of the illness and NS1 antigen levels were determined using both the Panbio dengue early ELISA (Panbio, Australia) and a NS1 rapid antigen detection kit (SD Bioline, South Korea). Results 59.1% of patients presented to hospital on day 5-6 of illness when NS1 antigen positivity was significantly (p = 0.008) associated with severe dengue (odds ratio 3.0, 95% CI 1.39 to 6.47) and the NS1 antigen levels were significantly higher (p = 0.03) in those who went on to develop shock. Serum NS1 antigen levels significantly (p < 0.0001) and inversely correlated with the total white cell counts and lymphocyte counts. The bedside NS1 test showed comparable sensitivity (97.4%) and specificity (93.7%) to the laboratory NS1 test in our setting and cohort. Conclusion NS1 antigen positivity is associated with a higher risk of developing severe dengue especially when positive beyond day 5 of illness in our cohort, and while further validation studies are required, the test can therefore potentially be used as a bedside point of care test as a warning sign of severe dengue. [ABSTRACT FROM AUTHOR]

Dengue virus (DENV) represents a major threat to public health worldwide. Early DENV diagnosis should not only detect the infection but also identify patients with a higher likelihood to develop severe cases. Previous studies have suggested the potential for NS1 to serve as a viral marker for dengue severity. However, further studies using different sera panels are required to confirm this hypothesis. In this context, we developed a lab-based ELISA to detect and quantitate NS1 protein from the four DENV serotypes and from primary and secondary cases. This approach was used to calculate the circulating NS1 concentration in positive samples. We also tested the NS1 positivity of DENV-positive samples according to the Platelia Dengue NS1 Ag assay. A total of 128 samples were positive for DENV infection and were classified according to the WHO guidelines. The overall NS1 positivity was 68% according to the Platelia assay, whereas all samples were NS1-positive when analyzed with our lab-based ELISA. Fifty-four samples were positive by PCR, revealing a co-circulation of DENV1 and DENV4, and the NS1 positivity for DENV4 samples was lower than that for DENV1. The circulating NS1 concentration ranged from 7 to 284 ng/mL. Our results support previous data indicating the low efficiency of the Platelia assay to detect DENV4 infection. Moreover, this work is the first to analyze NS1 antigenemia using retrospective samples from a Brazilian outbreak. [ABSTRACT FROM AUTHOR]

Background: Early diagnosis of dengue virus (DENV) infection can improve clinical outcomes by ensuring close follow-up, initiating appropriate supportive therapies and raising awareness to the potential of hemorrhage or shock. Non-structural glycoprotein-1 (NS1) has proven to be a useful biomarker for early diagnosis of dengue. A number of rapid diagnostic tests (RDTs) and enzyme-linked immunosorbent assays (ELISAs) targeting NS1 antigen (Ag) are now commercially available. Here we evaluated these tests using a well-characterized panel of clinical samples to determine their effectiveness for early diagnosis. Methodology/Principal Findings: Retrospective samples from South America were used to evaluate the following tests: (i) “Dengue NS1 Ag STRIP” and (ii) “Platelia Dengue NS1 Ag ELISA” (Bio-Rad, France), (iii) “Dengue NS1 Detect Rapid Test (1st Generation)” and (iv) “DENV Detect NS1 ELISA” (InBios International, United States), (v) “Panbio Dengue Early Rapid (1st generation)” (vi) “Panbio Dengue Early ELISA (2nd generation)” and (vii) “SD Bioline Dengue NS1 Ag Rapid Test” (Alere, United States). Overall, the sensitivity of the RDTs ranged from 71.9%–79.1% while the sensitivity of the ELISAs varied between 85.6–95.9%, using virus isolation as the reference method. Most tests had lower sensitivity for DENV-4 relative to the other three serotypes, were less sensitive in detecting secondary infections, and appeared to be most sensitive on Day 3–4 post symptom onset. The specificity of all evaluated tests ranged from 95%–100%. Conclusions: ELISAs had greater overall sensitivity than RDTs. In conjunction with other parameters, the performance data can help determine which dengue diagnostics should be used during the first few days of illness, when the patients are most likely to present to a clinic seeking care. [ABSTRACT FROM AUTHOR]

Serum samples from 150 NSl-negative (Platelia ELISA) patients presumptively diagnosed with dengue were analyzed by the TaqMan probed real-time reverse transcription PCR (TaqMan qRT-PCR) method. The qRT-PCR positive samples were tested for serotype by semi-nested RT-PCR and a qualitative immunochromatographic assay for IgG and IgM. Molecular detection methods showed 33 (22%) positive samples out of 150 NS1-antigen negative samples. Of these, 72% were collected up to day 2 after the onset of symptoms, when diagnostic sensitivity of NS1-antigen test assays is significantly enhanced. Most of the cases were not characterized as secondary infection. Twenty-eight samples were successfully serotyped, 75% of which for DENV-4, 14% for DENV-2, 7% for DENV-3 and 4% for DENV-1. These findings reaffirm the hyperendemic situation of the state of Roraima and suggest a lower sensitivity of the NS1 test, mainly when DENV-4 is the predominant serotype. Health care providers should therefore be aware of samples tested negative by NS1 antigen assays, especially when clinical symptoms and other laboratory data results show evidence of dengue infection. [ABSTRACT FROM AUTHOR]

Background All the reports from Angola’s 2013 dengue outbreak revealed serotype 1. However, previously dengue serotypes 1–4 have been reported in Africa and in 2014 serotype 4 was reported in Angola. Objectives To report dengue serotypes in patients returning from Angola during 2013 outbreak. Study design Retrospective, cross-sectional study. We serotyped the dengue by an in house Polymerase Chain Reaction technique in randomly selected cases. Results From the 2013 Angola’s dengue outbreak we treated 47 adult patients. None had history of past dengue. A combo kit test for dengue revealed positive NS1 antigen in 39 and IgM antibodies in 8. From 17 randomly patients tested by RNA Real Time-PCR, 11 were positive: 7 for DENV-1, 2 for DENV-2, 1 for DENV-3 (co-infected with DENV-1) and 1 for DENV-4. None had a complicated or fatal evolution. Conclusion Unlike previous reports the 4 serotypes were detected, and this resulted in a different epidemiological situation, raising the risk of future outbreaks of severe dengue. [ABSTRACT FROM AUTHOR]

Background and Objectives: The study was designed to assess the sensitivity of NS1 antigen ELISA test in Dengue fever in patients whose samples were received in the Microbiology Section, Department of Pathology, SIMS / Services Hospital, Lahore from October to December 2011. Methodology: Samples from clinically suspected cases of acute dengue fever irrespective of age and sex with available history of "day of fever" were included in this study. One hundred and thirteen blood samples were received in properly labeled disposable syringes along with request forms detailing patient information including the "day of fever". Dengue NS1 antigen ELISA tests were performed on the sera on the same day. Results: The NS1 antigen ELISA test positivity was 50 - 81 percent in the first six days of infection with dengue virus. After that, there was a gradual decline in the NS1 antigen positivity. Conclusions: NS1 antigen ELISA test has a high sensitivity in the first week of dengue infection. Therefore, it is suggested that laboratories that do not have sophisticated equipment or lack funds to do PCR can perform NS1 antigen ELISA test. [ABSTRACT FROM AUTHOR]

We report a dengue virus (DENV) co-infection in a Belgian traveler after a three-weeks holiday to Thailand. The patient recovered well without any complication. The infection was diagnosed by NS1 antigen testing and the concurrent presence of serotype DENV1 and DENV2 was demonstrated by reverse transcriptase polymerase chain reaction (RT-PCR) in acute phase serum sampled three days after symptoms onset. The predominant DENV1 serotype was identified as genotype I, lineage Asia-3 by sequencing. To our knowledge, this is the first time that a dengue co-infection is reported in a European traveler. The co-infection accounts for 1.0% of the total number of RT-PCR-positive samples ( n = 105) diagnosed in the reference laboratory of Belgium between 2008 and 2013. We expect that the number of reports on acute co-infections will increase in the coming years considering the increasing number of regions that are progressively becoming hyperendemic, especially in Southeast Asia. [ABSTRACT FROM AUTHOR]

Background: An outbreak of dengue infection occurred in Angul district of Odisha in the month of August & September, 2011. The study was undertaken to detect NS1 antigen positivity among the study population, to compare IgM capture ELISA with NS1 antigen detection for diagnosis of dengue and to identify the predominant genotype of Dengue virus responsible for the outbreak. Materials and Methods: Total 1020 serum samples were collected from clinically suspected cases of dengue from the outbreak. All were subjected for NS1 antigen detection, 92 were selected based on their clinical severity of illness (fever, rash, bleeding manifestation, arthralgia) for further study of IgM ELISA and platelet count and 148 NS1 positive samples were selected from different Blocks of Anugul district for RT-PCR at NIV, Pune, India. Results: Five hundred and thirteen (50.2%) samples were positive for NS1 antigen (highly significant p-value <0.0001, C.I - 95%) with 88% positivity during 1-5 days. The NS1 Ag positivity was peaked to 86.9% on days 3 to 5 (Sensitivity & NPV - 100% each) & declined to 6.2% during 6-10 days with a low sensitivity of 7.14% but 100% specificity & PPV. However, the IgM antibody positivity was 81.2% on days 6 to 10 and 87.5% after 10 days (Sensitivity- 100%, Specificity-13.33%,PPV-7.14% & NPV - 100%). RT-PCR resulted 32.4% positivity (6-DEN1, 39 - DEN 2 & 3- DEN 3) among which 20% were in IgM +ve & 68% in IgM -ve cases. Conclusion: Therefore, early diagnosis of dengue could be mainly by NS1 antigen detection whereas Ig M ELISA is a better tool during the later stage of infection &RT-PCR is more effective in IgM -ve cases.The predominant genotype responsible for the outbreak was found to be DEN-2. [ABSTRACT FROM AUTHOR]

Objectives: This aim of the study was to evaluate the efficacy of NS antigen assay for early diagnosis of dengue 1 virus infection in a tertiary care hospital. Methods: This cross sectional study was carried out in medicine unit of Square hospital from May to August 2013. Total 100 patients with dengue fever were included. Complete blood count, alanine aminotransferase (ALT), aspartate aminotransferase (AST), Dengue NS antigen and IgM and IgG antibodies of dengue virus were done in 1 all cases. Results: Of the 100 sera tested, 75% were positive for dengue virus infection based on dengue NS antigen, IgM 1 antibody and IgG antibody. Dengue NS antigen and IgM, IgG antibody were able to detect dengue virus infection 1 between day to day 8 in 92% of samples, 86.7% of samples and 82.6% of samples respectively. Sixty nine percent 1 (69%) were found positive for dengue NS antigen, 65% were IgM positive and 62% were IgG positive. Based on the 1 dengue NS antigen and IgM antibody combination, 74% were positive for dengue virus infections. Sensitivity of 1 Dengue NS antigen was 92.3% and specificity of 74.28% in comparison to IgM antibody. Based on the antigen and 1 IgG antibody combination, detection rate increased to 75%. Sensitivity of dengue NS antigen was 90.3% and 1 specificity of 65.8% in comparison to IgG antibody. Conclusion: Dengue NS antigen is a useful, sensitive and specific test for early diagnosis of dengue virus infection 1 and it improves diagnostic efficiency in combination with antibody test. [ABSTRACT FROM AUTHOR]

Background: Diagnosis of Dengue infection is essential for clinical care of patients with acute febrile illness. It has beendemon strated that combining NS1 Ag to an early serologic test improved Dengue diagnosis. If IgM has been extensively evaluated, there are few data about IgA detection in association to NS1. The purpose of these clinical studies was to evaluate the efficiency of combining dengue NS1 Ag and anti-NS1 IgA antibodies for the detection of Dengue infection during the acute phase in Asian populations. Methods & Materials: Evaluated kits were Platelia™ Dengue IgA Capture associated to Platelia™ Dengue NS1 Ag for ELISA part and RDT Dengue IgA/IgG associated to Dengue NS1 STRIP for rapid testing. Sensitivity was performed on 216 samples from patients with clinically confirmed Dengue of 3 Asian countries: Cambodia (n=135), India (n= 31) and Singapore (n=50). Specificity was evaluated on 101 sera from 50 healthy Indian donors and 51 febrile patients from Cambodia for which dengue infection has been excluded. Results: Depending on the population, the sensitivity ranged from 48.5% to 93.3% for Platelia™ Dengue IgA Capture assay versus 48.9% to 90.3% for IgM ELISA and 50% to 100% for the IgA rapid test. When NS1 and IgA tests were combined, the sensitivity reached 93.5% to 98.0% for the ELISAs and 94.1% to 100% for the rapid tests, compared to 94.9% for an "IgM+NS1" combination. The overall specificity of the NS1 and IgA combination in ELISA and rapid test assays were 95,9% and 96,0% respectively. The analysis of NS1 and IgA ELISAs sensitivity related to the sampling time after fever onset in Cambodia population showed that NS1 assay sensitivity was lower and decreased earlier (day 5) in secondary infection than in primary one (day 11). Conclusion: Detection of anti-NS1 IgA efficiently completesNS1 antigen detection in the diagnosis of acute dengue infection in Asian populations. The combination performs as well on ELISA as on rapid test format and demonstrates similar performance to "IgM+NS1". Moreover, IgA appears to be especially useful in secondary infections and has also been described to be indicative of more severe outcome in primary infections. [ABSTRACT FROM AUTHOR]