Abstract
BACKGROUND: This study examines the geographic distribution, temporal trends, and syndemic interactions between dengue and chikungunya outbreaks in India from 2014 to 2023, using data from the Integrated Disease Surveillance Programme (IDSP). Understanding trends offers critical insights to enhance public health responses to co-occurring vector-borne diseases. OBJECTIVES: The study analyzes the trends, geographic distribution, and syndemic interactions between dengue and chikungunya. It highlights patterns, high-burden areas, and seasonal dynamics to inform public health interventions for mitigating the dual burden. METHODS: This secondary data analysis used IDSP records from January 2014 to December 2023. Temporal trends in outbreaks were analyzed, and districts were categorized by severity through spatial mapping and bivariate analysis, employing statistical quartiles to assess the co-occurrence and syndemic nature of dengue and chikungunya. RESULTS: Dengue outbreaks increased significantly from 2014 to 2017, peaking at 175 outbreaks, followed by fluctuations until a peak of 200 outbreaks in 2023. In contrast, chikungunya outbreaks peaked in 2017 at 77 outbreaks and subsequently declined to 19 outbreaks by 2023. Geographic analysis indicated a high dengue burden in districts such as East Siang (Arunachal Pradesh), Birbhum (West Bengal), and Pune (Maharashtra), while chikungunya was most severe in Thanjavur, Theni, and Vellore (Tamil Nadu). A bivariate choropleth analysis identified regions with significant syndemic, such as Pune (Maharashtra), Tumkur (Karnataka), and Kamrup (Assam), which were classified as high-high. Additional districts such as Sangli and Satara (Maharashtra) were categorized as high-moderate, while Puducherry and Junagadh (Gujarat) were noted as moderate-high for dengue and chikungunya, respectively. CONCLUSIONS: The findings underscore significant variability in dengue and chikungunya syndemic across India, highlighting regions with severe dual burden. Enhanced surveillance for close watch on syndemic occurrence and its impact needs to be studied, which is essential to reduce both the incidence and study its compounded public health impacts.