Spatiotemporal dynamics and reemergence of chikungunya virus in Bangladesh from 2008 to 2025

OBJECTIVES: Despite being a major epidemic potential pathogen with recurrent emergence, chikungunya virus (CHIKV) remains neglected in Bangladesh, with poor characterization of long-term epidemiology, reemergence patterns, and prevention policy. METHODS: We screened epidemiologic, clinical, and genomic data on CHIKV outbreaks in Bangladesh from 2008 to 2025, integrating documents, national surveillance records, spatiotemporal trends, circulating genotypes, and public health gaps. RESULTS: Since its first documentation in 2008, the transmission of CHIKV has been characterized by prolonged inter-outbreak intervals. A major outbreak with >13,000 cases was documented in 2017, followed by a reemergence in 2024-2025 (2000 cases). Cases peaked invariably during post-monsoon months, with overlapping temporal and clinical features with dengue outbreaks. After 2015, the Indian Ocean lineage sub-clades carrying E1:K211E and E2:V264A mutations with enhanced Aedes aegypti adaptation were reported. Surveillance data indicate that substantial underreporting and underdiagnosis prevail due to symptom overlap with other febrile illnesses, limited decentralized diagnostic facilities, and the exclusion of CHIKV from routine national surveillance. Among the symptoms, fever and debilitating polyarthralgia affected >95% of symptomatic confirmed cases, with significant long-term (25-40% of patients with more than 6 months) morbidity and subsequent socioeconomic impact. CONCLUSIONS: Bangladesh is experiencing episodic but intensifying CHIKV transmission in recent years, after India, in the region. Integrating CHIKV into national routine surveillance, expanding affordable and available diagnostics, strengthening genomic surveillance, and implementing a sustained integrated vector management might be critical to reduce the impact of future outbreaks and regional spread.