Combining non-structural protein 1 and IgM tests for acute dengue diagnosis in Saudi Arabia

Dengue is endemic in Saudi Arabia, particularly in Jeddah, Makkah and Jizan. Outbreaks in these regions are mainly linked to climate conditions and mass travel during religious pilgrimages.

This retrospective cross-sectional study evaluated the diagnostic performance of the non-structural protein 1 (NS1) antigen test and IgM ELISA, compared with RT-PCR. A total of 2850 samples were collected from patients hospitalised with moderate to severe symptoms across six regions in Saudi Arabia from 2022 to 2024. The samples were tested simultaneously using all three methods and 95% CIs were calculated using the Wilson score method.

Out of 3419 samples analysed, 1402 tested negative for dengue and 1448 tested positive. The sensitivity of the NS1 antigen test was 73.5% (95% CI 70.7 to 76.2%). The IgM ELISA test demonstrated a sensitivity of 65.8% (95% CI 62.9 to 68.7%). Combining the results of both tests increased the sensitivity to 92.4% (95% CI 90.6 to 93.9%). This combined diagnostic approach facilitates the detection of both early-phase (NS1-positive) and later-phase (IgM-positive) infections, offering a more comprehensive diagnostic tool.

Implementing a combined testing strategy within Saudi Arabia's diagnostic pipelines could enhance disease surveillance, enable earlier detection and strengthen public health efforts against dengue outbreaks.