Commercially available diagnostic test kits for detection of dengue virus (DENV) non-structural protein 1 (NS1) and anti-DENV IgM were evaluated for their sensitivity and specificity and other performance characteristics by a diagnostic laboratory network developed by World Health Organization (WHO), the UNICEF/UNDP/World Bank/WHO Special Programme for Research and Training in Tropical Diseases (TDR) and the Pediatric Dengue Vaccine Initiative (PDVI). Each network laboratory contributed characterized serum specimens for the panels used in the evaluation. Microplate enzyme-linked immunosorbent assay (ELISA) and rapid diagnostic test (RDT formats) were represented by the kits. Each ELISA was evaluated by 2 laboratories and RDTs were evaluated by at least 3 laboratories. The reference tests for IgM anti-DENV were laboratory developed assays produced by the Armed Forces Research Institute for Medical Science (AFRIMS) and the Centers for Disease Control and Prevention (CDC), and the NS1 reference test was reverse transcriptase polymerase chain reaction (RT-PCR). Results were analyzed to determine sensitivity, specificity, inter-laboratory and inter-reader agreement, lot-to-lot variation and ease-of-use. NS1 ELISA sensitivity was 60–75% and specificity 71–80%; NS1 RDT sensitivity was 38–71% and specificity 76–80%; the IgM anti-DENV RDTs sensitivity was 30–96%, with a specificity of 86–92%, and IgM anti-DENV ELISA sensitivity was 96–98% and specificity 78–91%. NS1 tests were generally more sensitive in specimens from the acute phase of dengue and in primary DENV infection, whereas IgM anti-DENV tests were less sensitive in secondary DENV infections. The reproducibility of the NS1 RDTs ranged from 92-99% and the IgM anti-DENV RDTs from 88–94%. Dengue virus (DENV) infection occurs throughout tropical and sub-tropical regions of the world where dengue is a major public health problem. Laboratory diagnosis of dengue with a single serum specimen obtained during the acute phase of the illness requires tests to detect IgM antibodies to DENV or the virus genome. A previous evaluation of available tests for IgM anti-DENV showed wide variability. The present study examined newly available commercial tests that detect the virus protein NS1, as well as new tests for IgM anti-DENV in microplate or rapid diagnostic test formats. This analytic study used specimens from laboratory confirmed dengue patients worldwide, which makes the results widely generalizable. The study found variability among the microplate ELISAs for both analytes but some tests performed with sensitivity and specificity acceptable for routine dengue diagnostics. The RDT's for both analytes had variable sensitivity that could be considered acceptable for routine clinical diagnostics. There is the need to maintain a network of dengue reference laboratories to conduct similar evaluations as additional dengue diagnostic tests become commercially available in order to guide the use for surveillance, clinical diagnosis and research.

Dengue virus (DENV) nonstructural protein 1 (NS1) has shown promise as a novel diagnostic marker of acute DENV infection. Current techniques used to diagnose acute DENV infection, including virus isolation and reverse transcription-PCR (RT-PCR), are costly and difficult to perform, while traditional serological assays have low sensitivities during the acute stage of infection. Two commercially available NS1 antigen capture enzyme-linked immunosorbent assays (ELISAs), the Platelia dengue NS1Ag test (Bio-Rad Laboratories, Marnes La Coquette, France) and the Pan-E dengue early ELISA test (Panbio Diagnostics, Brisbane, Australia), were evaluated against a well-characterized panel of 208 real-time RT-PCR- and virus isolation-positive sera, as well as 45 real-time RT-PCR- and serologically negative sera from patients with other acute febrile illnesses. The overall sensitivities were 64.9% (95% confidence interval [CI₉₅], 58.2 to 71.1%) for the Panbio test and 83.2% (CI₉₅, 77.5 to 87.7%) for the Bio-Rad test, with interserotype variation, especially for DENV serotype 4. Predictive models were constructed to identify factors that had a significant influence on a test's outcome with respect to this panel of samples in order to identify the conditions in which the test will be most effective as a diagnostic tool. The immunoglobulin G titer was found to be the only covariate that significantly influenced results in the Bio-Rad test, while serotype and the day postonset were found to significantly influence results in the Panbio test. We concluded that the NS1 capture ELISA is a useful tool that can improve testing algorithms to diagnose DENV infection in single samples from acute and early convalescent cases.

Background. Anti–dengue virus (DENV) immunoglobulin M (IgM) seroconversion has been the reference standard for dengue diagnosis. However, paired specimens are rarely obtained, and the interval for this testing negates its usefulness in guiding clinical case management. The presence of DENV viremia and appearance of IgM during the febrile phase of dengue provides the framework for dengue laboratory diagnosis by using a single serum specimen. Methods. Archived paired serum specimens (n = 1234) from patients with laboratory-confirmed dengue from 2005 through 2011 were used to determine the diagnostic performance of real-time reverse transcription polymerase chain reaction (RT-PCR), for detection of DENV serotypes 1–4, and enzyme-linked immunosorbent assays (ELISAs), for detection of DENV nonstructural protein 1 (NS1) antigen and anti-DENV IgM. Results. During 1–3 days after illness onset, real-time RT-PCR and NS1 antigen testing detected 82%–69% and 90%–84% of cases, respectively, as viremia levels declined, while anti-DENV IgM ELISA detected 5%–41% of cases as antibody appeared. Over the 10-day period of the febrile phase of dengue, the cumulative effect of using these 3 types of tests in a diagnostic algorithm confirmed ≥90% of dengue cases. Conclusions. The use of molecular or NS1 antigen tests to detect DENV and one to detect anti-DENV IgM in a single serum specimen collected during the first 10 days of illness accurately identified ≥90% of dengue primary and secondary cases.

A West Nile virus (WNV) infection in humans can produce neurological symptoms including acute flaccid paralysis, encephalitis, meningitis and myelitis. To investigate the pathogenesis of WNV in the...

Dengue is major public health problem, globally. Timely verification of suspected dengue outbreaks allows for public health response, leading to the initiation of appropriate clinical care. Because the clinical presentation of dengue is nonspecific, dengue diagnosis would benefit from a sensitive rapid diagnostic test (RDT). We evaluated the diagnostic performance of an RDT that detects dengue virus (DENV) nonstructural protein 1 (NS1) and anti-DENV IgM during suspected acute febrile illness (AFI) outbreaks in four countries. Real-time reverse transcription-PCR and anti-DENV IgM enzyme-linked immunosorbent assay were used to verify RDT results. Anti-DENV IgM RDT sensitivity and specificity ranged from 55.3 to 91.7% and 85.3 to 98.5%, respectively, and NS1 sensitivity and specificity ranged from 49.7 to 92.9% and 22.2 to 89.0%, respectively. Sensitivity varied by timing of specimen collection and DENV serotype. Combined test results moderately improved the sensitivity. The use of RDTs identified dengue as the cause of AFI outbreaks where reference diagnostic testing was limited or unavailable.