EFFECT OF CLIMATIC CHANGES ON REPORTED DENGUE CASES IN SRI LANKA: A RETROSPECTIVE STUDY FROM YEAR 2020 TO 2024

Abstract

Dengue fever remains a significant public health challenge in Sri Lanka, with rising incidence and expanding geographic distribution in recent years. This study investigates the spatial and temporal variations of dengue cases in relation to mortality patterns and their potential associations with climatic factors from 2020 to 2024. District-level data on dengue cases and deaths were obtained from national surveillance systems, alongside rainfall and temperature data from 21 districts. Statistical analyses, including Chi-square tests and linear-by-linear association models, were employed to assess relationships between dengue outcomes and climatic variables using SPSS version 25. The analysis also considered disruptions in disease surveillance during the COVID-19 pandemic. Colombo and Gampaha consistently reported the highest burdens, peaking in 2023 with 18,911 and 16,127 cases, respectively. Mortality reached its maximum in 2022 (72 deaths), followed by 62 in 2023 and 23 in 2024. A significant decline in cases was observed in 2020, with a 79% reduction in Colombo compared to 2019 (p < 0.001), which coincided with the implementation of COVID-19 restrictions. Dengue cases and deaths were strongly correlated in all years (2021: r = 0.756, p < 0.01; 2022: r = 0.808, p < 0.01; 2023: r = 0.878, p < 0.01; 2024: r = 0.718, p < 0.01). Rainfall was not significantly associated with dengue cases overall (p = 0.236), but in 2024 showed a significant positive trend with both cases (p = 0.019) and deaths (p = 0.012). Temperature showed no significant association with cases or deaths in any year (all p > 0.05). In conclusion, dengue transmission in Sri Lanka shows strong spatial variation, with urban districts most affected. Although rainfall had a significant impact in 2024, overall climate factors showed limited predictive value for 2020–2024. Integrating epidemiological and climate surveillance is advised to enhance climate-sensitive dengue preparedness.