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Literature Sharing: Evaluating a rapid molecular assay in a mobile laboratory for improved diagnosis of dengue in Bangladesh
Release date:
2025-12-15
Dengue fever is a major global public health threat, particularly in Bangladesh, where the epidemic has become increasingly severe in recent years.
Source： International Journal of Infectious Diseases 150 (2025) 107299
I. Research Background and Objectives
Dengue fever is a major global public health threat, particularly in Bangladesh, where the epidemic has become increasingly severe in recent years. In 2023, over 320,000 cases and 1,705 deaths were reported. A key challenge is the rising proportion of secondary dengue infections, which are associated with more severe clinical manifestations and higher mortality rates.
Currently, Bangladesh primarily relies on NS1 antigen Rapid Diagnostic Tests (RDT) for diagnosis. However, the sensitivity of NS1 RDT drops significantly when diagnosing secondary infections, easily leading to missed diagnoses, delayed treatment, and impacting public health surveillance.
This study aims to evaluate the diagnostic performance of a novel rapid molecular detection technology—RT-RAA (Reverse Transcription Recombinase-Aided Amplification)—on a mobile suitcase laboratory platform. The researchers compared it with NS1 RDT, IgM RDT, and conventional reverse transcriptive-polymerase chain reaction (qRT-PCR), with a specific focus on its performance in identifying primary and secondary dengue infections.
II. Research Methods
1. Study Subjects: A total of 364 suspected dengue patients were enrolled. The diagnostic criterion was a positive result in any one of the following tests: NS1 RDT, IgM RDT, RT-RAA, or qRT-PCR.
2. Infection Type Classification: IgG RDT results were used to distinguish between primary and secondary infections.
3. Detection Methods:
◦ RT-RAA: Performed in a mobile suitcase laboratory, using rapid heat lysis for RNA extraction, with results available within 30 minutes.
◦ Reference Methods: NS1 RDT, IgM RDT, and laboratory-based qRT-PCR.
III. Key Findings
1. Results: Among the 364 suspected patients, 320 (87.9%) were confirmed to have dengue fever. Of these, 55.94% were primary infections and 44.06% were secondary infections.
2. Differences in Clinical Manifestations: The study found significant differences in symptoms between secondary and primary infections. Patients with secondary infections experienced fever for longer durations and were more likely to present with nausea, retro-orbital pain, oral ulcers, sore throat, and cough.
3. Comparison of Detection Performance for Primary vs. Secondary Infections in Clinical Samples:
◦ For primary infections: NS1 RDT and RT-RAA showed similarly high positive detection rates (77.1% and 78.8%, respectively).
◦ For secondary infections: The advantage of RT-RAA was extremely pronounced, with a positive detection rate as high as 76.6%, while the rate for NS1 RDT plummeted to 27%. The positive detection rate for qRT-PCR was stable at 60.3%, and IgM RDT had the lowest detection rate at 24.8%.
4. Comparison of Detection Performance During Acute and Post-Acute Phases: RT-RAA maintained a high detection rate throughout the first 8 days after symptom onset. The sensitivity of NS1 RDT began to decline after day 4, while the sensitivity of qRT-PCR and IgM RDT increased in the later phase but remained lower than that of RT-RAA.
5. Combination Testing: The study evaluated the effect of combining NS1 RDT with other detection methods.
◦ In secondary dengue, using NS1 RDT alone detected only 27% of cases.
◦ If NS1 RDT was combined with RT-RAA, the detection rate could be significantly increased to 81.56%.
◦ This indicates that RT-RAA can effectively compensate for the major gap in NS1 RDT's ability to diagnose secondary infections.
IV. Discussion and Conclusion
This study confirms that, within the context of the dengue epidemic in Bangladesh, the existing primary diagnostic tool, NS1 RDT, has serious shortcomings in detecting secondary infections. In contrast, the RT-RAA technology, with its advantages of high sensitivity, speed (results in 30 minutes), portability (suitcase laboratory), and relatively low cost (<$10 per sample), presents a highly promising complementary diagnostic solution.
Conclusion: Combining RT-RAA testing with NS1 RDT can significantly improve the overall detection rate for dengue fever, particularly for the higher-risk secondary infections. This combined strategy can contribute to more timely clinical intervention and more accurate public health surveillance.
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