Nur Ain Zahidah Zainudin1*, Jeyanthi Suppiah1, Murni Maya Sari Zulkifli1, Amir Hussin Adiee1, Mohd Effendy Dukut Soeharto1, Rozainanee Mohd Zain1
1. Virology Unit, Infectious Disease Research Centre (IDRC), National Institutes of Health (NIH), Setia Alam, Selangor, Malaysia
*Corresponding author: Nur Ain Zahidah Zainudin.
ABSTRACT
INTRODUCTION: Dengue is a mosquito-borne viral infection caused by four distinct serotypes (DENV1–4), primarily transmitted by Aedes aegypti. Accurate serotyping is crucial for clinical management, as certain serotypes are associated with more severe disease. Real-time reverse transcription PCR (RT-qPCR) remains the gold standard for early detection and serotyping while cycle threshold (Ct) values provide an indirect estimate of viral load that informs transmission risk. However, local data integrating serotype prevalence with demographics, region, and Ct values remain limited.
OBJECTIVE(S): This study aims to characterize the serotype distribution, patient demographics and Ct values of dengue cases diagnosed in 2024 at the Virology Unit, Institute for Medical Research (IMR).
MATERIALS & METHODS: This was a retrospective, observational study utilizing a dataset of 412 dengue-positive diagnostic samples received for routine RT-qPCR testing at the Virology Unit, IMR from January to December 2024. Data analysis involved descriptive statistics and Chi-Square tests to determine associations between dengue serotypes, patient demographics and Ct values.
RESULTS: DENV2 was the most prevalent serotype in the year 2024 (67.5%), followed by DENV3 (15.0%), DENV4 (9.0%), and DENV1 (8.5%). A significant association was found between serotype and age group (p=0.005), with the 26–44 age group having the highest case concentration across all serotypes, indicating age-specific serotype distribution. Serotype distribution varied significantly by locality (p < 0.001). DENV2 was the most prevalent serotype in Kedah, Kelantan, Johor, and Selangor. DENV3 was primarily concentrated in Johor, while DENV4 was more common in Selangor and Johor. DENV1 was notably prominent in Kelantan. A significant association was also observed between serotypes and Ct value ranges (p < 0.001). DENV4 exhibited a significantly higher Ct range (30.01–40.00), indicating relatively lower viremia, whereas DENV2 showed a lower Ct range (10.01–20.00), suggesting higher viremia.
CONCLUSION: These results show that dengue serotype prevalence varies by age and location, highlighting the importance of sustained epidemiological monitoring to guide public health interventions and track evolving transmission patterns. Incorporating clinical presentations and viremic phase data may yield more clinically relevant insights.
KEYWORDS: Dengue, Serotypes, RT-qPCR
