Dengue Rapid Diagnostic Kit Field Evaluated

Dengue diagnosis is complex and until recently, only specialized laboratories were able to definitively confirm dengue infection, but the rapid tests are now available commercially making biological diagnosis possible in low resource settings.

Scientists at the Pasteur Institute (Phnom Penh, Cambodia) enrolled 157 patients hospitalized for a suspicion of dengue in a prospective study between June and October 2011. A panel of sera were chosen for positive and negative control and tested with reverse transcriptase polymerase chain reaction (RT-PCR), in-house immunoglobulin M (IgM) capture enzyme-linked immunosorbent assay (MAC-ELISA), and a hemagglutination inhibition assay.

The rapid diagnostic used was the SD Bioline Dengue Duo kit (Standard Diagnostics (Kyonggi-do, Korea) and for the prospective study, only acute blood samples were tested. The SD Bioline Dengue Duo kit is composed of two tests designed to detect DENV NS1 antigen as a first test and anti-DENV IgM/IgG as a second test in serum, plasma, or whole blood. In the field hospital laboratories, the overall sensitivity was 85.7% and the specificity was 83.9% of the NS1/IgM/IgG combination tests, whereas in the national reference laboratory, the sensitivity was 94.4%, and the specificity was 90.0%.

The results of the study demonstrated that optimal performances require adequate training and quality assurance. The retrospective study showed that the sensitivity of the combined kit did not vary significantly between the serotypes and was not affected by the immune status or by the interval of time between onset of fever and sample collection. However, in the context of the prospective field study, it was shown that if the SD Bioline Dengue Duo kit is correctly used, a positive result highly suggests a dengue case, but a negative result does not rule out a dengue infection.

The authors concluded that when they assessed the impact of the test results on the clinical management decision, the physicians treated patients according to their clinical diagnosis and did not take negative results into consideration. The combination of NS1 test with antibodies detection improved the performance, though discordances on IgM and IgG results were observed between the hospitals and the national reference laboratories. The study was published online in December 2012 in the journal Public Library of Science Neglected tropical Diseases.

Related Links:
Cambodian Pasteur Institute
Standard Diagnostics