Prior to their commercial availability within the last 15 years, dengue diagnostics were available only in a limited number of government supported research laboratories in the Americas and Asia. Even today with commercially available diagnostic tests, the accurate diagnosis of acute dengue virus infection, including primary and secondary infections, requires a laboratory with capacity to perform several immunodiagnostic assays and to carry out virus detection by cell culture or nucleic acid detection. A number of research based assays are required to determine if a person is immune to infection from a specific dengue virus serotype, whether a person has cross reacting (heterotypic) antibody to dengue viruses and whether a person had been infected with a Flavivirus other than dengue.

The development in the early 1990’s of an ELISA to detect IgM antibodies to dengue virus and its subsequent commercial availability has improved the capability to diagnose acute dengue virus infection. However, IgM antibody to dengue becomes detectable only 4-7 days after onset of fever, which limits its usefulness in the clinical setting, where patients often present within 2-4 days of fever onset. In addition, these tests have not been rigorously evaluated against a panel of well characterized specimens. In one limited evaluation, the positive predictive value of several commercially available tests was <70%. Recently there has been increased effort to develop tests to diagnose acute infection more accurately, including nucleic acid detection in various amplification formats and ELISAs to detect circulating NS1 antigen. However, these tests are available only in specialized laboratories that produce their own reagents.

Assays for serotype-specific antibody against infection include the plaque reduction neutralization test (PRNT), an IgG ELISA and a hemagglutination inhibition (HI) assay. As with most dengue diagnostics, these tests are not commercially available, except for the IgG ELISA, and have rarely been evaluated against panels of well characterized serum specimens to determine their sensitivity, specificity and positive or negative predictive values. Even for the PRNT, there is not good correlation of results between research or reference laboratories performing the assay.

Well standardized assays for acute infection and serotype-specific protective antibody to dengue virus infection are needed for vaccine evaluation. While sponsors of vaccine trials will qualify existing assays to meet regulatory requirements, there is the need to have assays that are comparable between groups conducting clinical trials. In addition, when dengue vaccine becomes available, the ongoing assessment of its effectiveness will require the accurate diagnosis of acute infection and well standardized assays to measure long-term protection.